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. 2020 Aug 19;17(8):e1003208. doi: 10.1371/journal.pmed.1003208

Variation in antibiotic prescription rates in febrile children presenting to emergency departments across Europe (MOFICHE): A multicentre observational study

Nienke N Hagedoorn 1, Dorine M Borensztajn 1, Ruud Nijman 2, Anda Balode 3, Ulrich von Both 4,5, Enitan D Carrol 6,7, Irini Eleftheriou 8, Marieke Emonts 9,10,11, Michiel van der Flier 12,13,14, Ronald de Groot 12,13, Jethro Herberg 2, Benno Kohlmaier 15, Emma Lim 9,10, Ian Maconochie 16, Federico Martinon-Torres 17, Daan Nieboer 18, Marko Pokorn 19, Franc Strle 19, Maria Tsolia 8, Shunmay Yeung 20, Dace Zavadska 3, Werner Zenz 15, Clementien Vermont 21, Michael Levin 2, Henriëtte A Moll 1,*; on behalf of the PERFORM consortium
Editor: Jean-Louis Vincent22
PMCID: PMC7444592  PMID: 32813708

Abstract

Background

The prescription rate of antibiotics is high for febrile children visiting the emergency department (ED), contributing to antimicrobial resistance. Large studies at European EDs covering diversity in antibiotic and broad-spectrum prescriptions in all febrile children are lacking. A better understanding of variability in antibiotic prescriptions in EDs and its relation with viral or bacterial disease is essential for the development and implementation of interventions to optimise antibiotic use. As part of the PERFORM (Personalised Risk assessment in Febrile illness to Optimise Real-life Management across the European Union) project, the MOFICHE (Management and Outcome of Fever in Children in Europe) study aims to investigate variation and appropriateness of antibiotic prescription in febrile children visiting EDs in Europe.

Methods and findings

Between January 2017 and April 2018, data were prospectively collected on febrile children aged 0–18 years presenting to 12 EDs in 8 European countries (Austria, Germany, Greece, Latvia, the Netherlands [n = 3], Spain, Slovenia, United Kingdom [n = 3]). These EDs were based in university hospitals (n = 9) or large teaching hospitals (n = 3). Main outcomes were (1) antibiotic prescription rate; (2) the proportion of antibiotics that were broad-spectrum antibiotics; (3) the proportion of antibiotics of appropriate indication (presumed bacterial), inappropriate indication (presumed viral), or inconclusive indication (unknown bacterial/viral or other); (4) the proportion of oral antibiotics of inappropriate duration; and (5) the proportion of antibiotics that were guideline-concordant in uncomplicated urinary and upper and lower respiratory tract infections (RTIs). We determined variation of antibiotic prescription and broad-spectrum prescription by calculating standardised prescription rates using multilevel logistic regression and adjusted for general characteristics (e.g., age, sex, comorbidity, referral), disease severity (e.g., triage level, fever duration, presence of alarming signs), use and result of diagnostics, and focus and cause of infection. In this analysis of 35,650 children (median age 2.8 years, 55% male), overall antibiotic prescription rate was 31.9% (range across EDs: 22.4%–41.6%), and among those prescriptions, the broad-spectrum antibiotic prescription rate was 52.1% (range across EDs: 33.0%–90.3%). After standardisation, differences in antibiotic prescriptions ranged from 0.8 to 1.4, and the ratio between broad-spectrum and narrow-spectrum prescriptions ranged from 0.7 to 1.8 across EDs. Standardised antibiotic prescription rates varied for presumed bacterial infections (0.9 to 1.1), presumed viral infections (0.1 to 3.3), and infections of unknown cause (0.1 to 1.8). In all febrile children, antibiotic prescriptions were appropriate in 65.0% of prescriptions, inappropriate in 12.5% (range across EDs: 0.6%–29.3%), and inconclusive in 22.5% (range across EDs: 0.4%–60.8%). Prescriptions were of inappropriate duration in 20% of oral prescriptions (range across EDs: 4.4%–59.0%). Oral prescriptions were not concordant with the local guideline in 22.3% (range across EDs: 11.8%–47.3%) of prescriptions in uncomplicated RTIs and in 45.1% (range across EDs: 11.1%–100%) of prescriptions in uncomplicated urinary tract infections. A limitation of our study is that the included EDs are not representative of all febrile children attending EDs in that country.

Conclusions

In this study, we observed wide variation between European EDs in prescriptions of antibiotics and broad-spectrum antibiotics in febrile children. Overall, one-third of prescriptions were inappropriate or inconclusive, with marked variation between EDs. Until better diagnostics are available to accurately differentiate between bacterial and viral aetiologies, implementation of antimicrobial stewardship guidelines across Europe is necessary to limit antimicrobial resistance.


Henriette Moll and colleagues assess how antibiotic prescribing rates differ across twelve emergency departments in eight European countries.

Author summary

Why was this study done?

  • Respiratory infections, which are mainly caused by viruses, account for the majority of antibiotic use in children. In children with respiratory infections, antibiotic prescription rates vary across emergency departments (EDs) in Europe.

  • In order to optimise antibiotic prescriptions, it is important to better understand variability and appropriateness in antibiotic prescriptions.

What did the researchers do and find?

  • In this prospective observational study, we included routine information of 35,650 children (median age 2.8 years) with fever attending 12 different EDs in Europe and calculated the proportion of antibiotic prescriptions and broad-spectrum antibiotic prescriptions. We adjusted for differences in population including age, comorbidity, disease severity, and focus and cause of infection.

  • Across EDs, antibiotic prescription rates ranged between 22.4% and 41.6%, and of these prescriptions, broad-spectrum antibiotic rates ranged between 33.0% and 90.3%. Standardised antibiotic prescription rates ranged between 0.77 and 1.35, and standardised rates of broad-spectrum antibiotics ranged between 0.65 and 1.75.

  • Prescriptions that were inappropriately indicated ranged from 0.6% to 29.3%, and inconclusive prescriptions ranged from 0.5% to 61.7%. The proportion of oral prescriptions with inappropriate duration ranged from 4.4% to 59.0%.

What do these findings mean?

  • In this study we found variation of prescription of antibiotics and broad-spectrum antibiotics between EDs in children with fever, even when correcting for age, comorbidity, disease severity, diagnostics, and focus and cause of infection.

  • Variation was especially large in prescriptions for viral infections and infections of unknown cause.

  • In this cohort of febrile children, one-third of prescriptions were of inappropriate or inconclusive indication, with variation between EDs. In addition, guideline concordance for respiratory and urinary infections varied widely across EDs.

  • Generalisation of these results to all EDs in Europe should be undertaken with caution.

  • Implementation of guidelines is needed to improve appropriate prescription of antibiotics, whilst new biomarkers will further improve antibiotic prescription.

Introduction

Fever is one of the most common reasons for children to visit the emergency department (ED), and most visits are accounted for by self-limiting infections [1,2]. The proportion of children with a serious bacterial infection that needs treatment with antibiotics ranges from 7% to 13%, while antibiotic prescription rates in febrile children at EDs are between 19% and 64% [35]. Inappropriate antibiotic use, including the unnecessary use of broad-spectrum antibiotics, remains high in children, promoting the emergence of antimicrobial resistance [69]. Inappropriate antibiotic prescriptions were described in around 30% of outpatient prescriptions. However, these outpatient settings mainly involve primary care, and limited studies are available on specific emergency care [6,10].

Large variability exists between countries in antibiotic prescriptions in inpatient and outpatient settings, according to several large studies [6,8,1114]. In general, these large studies did not adjust for differences in populations. In children, previous studies have demonstrated substantial variation of antibiotic use in general outpatient settings in the United States and Europe, indicating possible overuse of antibiotics [5,6,10,15].

A literature review on antibiotic prescription rates and their determinants in febrile children in emergency care found large heterogeneity of studied populations, which limited the ability to draw conclusions [16]. One recent European study, focusing solely on EDs, showed significant differences in antibiotic prescription rates in otherwise healthy children with respiratory tract infections (RTIs) [5]. Large studies at EDs across Europe are lacking that cover antibiotic and broad-spectrum prescriptions in all febrile children, including patients with comorbidity, patients with detailed clinical information, and patients in different diagnostic groups. Additionally, previous studies have addressed appropriate prescribing based on diagnosis coded with the International Classification of Diseases [6,10,17]. This classification, however, may not accurately take into account bacterial versus viral aetiology. Antibiotic prescription rates for viral and bacterial disease using a structured classification have not yet been investigated at EDs.

A better understanding of variability in antibiotic prescriptions in EDs and its relation with bacterial or viral disease, taking into account differences in case mix, is essential for the development and implementation of interventions to optimise antibiotic use. In addition, knowledge regarding variation of prescribing in infections where antibiotic prescription is inappropriate, such as prescriptions in viral disease, prescriptions of inappropriate duration, or prescriptions that are not concordant with guidelines, could target and improve implementation of antimicrobial stewardship guidelines at the ED level.

In this study, we aim to investigate the variation and appropriateness of rates and types of antibiotic prescription in febrile children attending 12 different EDs in Europe.

This is a main analysis of the MOFICHE (Management and Outcome of Fever in Children in Europe) study, which is embedded in the PERFORM (Personalised Risk assessment in Febrile illness to Optimise Real-life Management across the European Union) project (https://www.perform2020.org) [18]. MOFICHE is an observational multicentre study that studies the management and outcome of febrile children in Europe using routine data. The overall aim of PERFORM is to improve management of febrile children and to improve diagnosis through development of new diagnostic tests to discriminate viral and bacterial infections in children.

Methods

Study design

MOFICHE is a prospective observational study using data that are collected as part of routine care. This study is reported as per the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline (S1 Text), and data were analysed using an a priori statistical analysis plan (S2 Text). The study was approved by the ethics committees in the participating hospitals, and the need for informed consent was waived (S3 Text).

Study population and setting

Children aged 0–18 years presenting with fever (temperature ≥ 38.0°C) or a history of fever (fever within 72 hours before ED visit) were included. Twelve EDs from 8 European countries participated in this study: Austria, Germany, Greece, Latvia, the Netherlands (n = 3), Spain, Slovenia, and the United Kingdom (n = 3). The EDs were included because they all participated in the PERFORM project. Characteristics of these EDs are described in S4 Text and in a previous publication [19]. In short, the participating hospitals were either university hospitals (n = 9) or large teaching hospitals (n = 3), and 11 EDs had paediatric intensive care facilities. Nine EDs were paediatric focused, and 3 EDs served both children and adults. Care for febrile children was supervised by general paediatricians (7 EDs), by paediatric emergency physicians (2 EDs), or by a general paediatrician or a (paediatric) emergency physician (3 EDs). All data were available in electronic healthcare records in 5 EDs, 1 ED used paper records, and 6 EDs used a combination of paper and electronic healthcare records.

Data were collected from January 2017 until April 2018, and for at least 1 year at each site to include all seasons. The period of data collection per month ranged from 1 week per month to the whole month in the participating hospitals (S4 Text).

Sample size

We expected to include 40,000 children with at most 5% missing data. Pilot data showed an overall antibiotic prescription rate of 30%. Applying 10 events per variable, this study is large enough to analyse over 1,000 determinants for the outcome antibiotic prescription [20]. We performed a post hoc sample size estimation for a desired width of the 95% confidence interval (CI) of standardised antibiotic prescription rate per ED. The expected width of the CI of the standardised prescription rate was below 0.5 for the smallest ED.

Data collection

Data were collected as part of routine ED care. The local research team entered data from patient records in an electronic case record form (eCRF) [21]. Collected data included age, sex, season, referral, comorbidity (chronic condition expected to last at least 1 year) [22], triage urgency, fever duration, fever measured at ED, presence of “red traffic light” symptoms for identifying risk of serious illness (alarming signs) (from the National Institute for Health and Care Excellence [NICE] guideline on fever [23]: decreased consciousness, ill appearance, work of breathing, meningeal signs, focal neurology, non-blanching rash, dehydration, status epilepticus), previous antibiotic use, vital signs (heart rate, respiratory rate, oxygen saturation, temperature, capillary refill time), laboratory results (white blood cell count, C-reactive protein [CRP], urinalysis), imaging (chest X-ray and other imaging), microbiological investigations (cultures and respiratory viral tests), and disposition (intensive care unit admission, general ward admission or discharge). We collected data on antibiotics prescribed in the ED or started on the first day of hospital admission (type, route of administration, and duration). The focus of infection was categorised as upper respiratory tract (otitis media, tonsillitis/pharyngitis, other), lower respiratory tract, gastrointestinal tract, urinary tract, skin, musculoskeletal, sepsis, central nervous system, flu-like illness, childhood exanthem, inflammatory syndrome, undifferentiated fever, or other.

To date, no reference standard exists to classify the cause of infection in routine ED practice [24]. The PERFORM consortium adapted the consensus-based flowchart from Herberg and colleagues [25,26], combining all available clinical data, investigation results such as CRP, cultures, and imaging. This flowchart was used to define the presumed cause of infection for each patient visit: definite bacterial, probable bacterial, bacterial syndrome, unknown bacterial/viral, viral syndrome, probable viral, definite viral, trivial, inflammatory syndrome, and other (Fig 1). The diagnosis definite bacterial infection was assigned only when a sterile site culture identified pathogenic bacteria. The diagnosis ‘probable bacterial infection’ was assigned when a bacterial syndrome was suspected but no bacteria were identified and CRP was above 60 mg/l. Patients with clinical bacterial symptoms and CRP ≤ 60 mg/l or no CRP were classified as ‘bacterial syndrome’. Children with suspected viral infections were classified as ‘viral syndrome’ (no CRP or CRP > 60 mg/l) or ‘definite viral’ (CRP ≤ 60 mg/l) when a virus was identified that matched the clinical symptoms. Children with a viral syndrome and CRP ≤ 60 mg/l, but no identified virus, were classified as ‘probable viral’. Children who did not fit these definitions were classified as unknown bacterial/viral. Children with mixed infections (bacterial and viral co-infection) were classified as bacterial. Children with trivial infections, inflammatory syndrome, or other infections were classified as ‘other’.

Fig 1. Categorisation of presumed cause of infection.

Fig 1

CRP, C-reactive protein; LRTI, lower respiratory tract infection; URTI, upper respiratory tract infection. *Patients could have identified viral co-infection.

We aimed to improve data quality and standardised data collection by using a training module for the local clinical and research teams to optimise clinical assessment and data collection for febrile children. This training module included clarification of the individual alarming signs and classification examples of common diagnoses. Furthermore, entry guidelines for the eCRF were available, monthly teleconferences and biannual meetings were organised, and quarterly reports of data quality for each ED were discussed. These consortium teleconferences also included discussion of difficult cases.

Antibiotic classification

Antibiotics were categorised using the Anatomical Therapeutic Chemical classification including beta-lactamase sensitive penicillins (J01CE); beta-lactamase resistant penicillins (J01CF); penicillins with extended spectrum (J01CA); combinations of penicillins including beta-lactamase inhibitors (J01CR); macrolides (J01FA); first-generation, second-generation, and third-generation cephalosporins (J01DB, J01DC, J01DD); trimethoprim and sulphonamides (J01EA01, J01EE01); aminoglycosides (J01GB); quinolones (J01MA); glycopeptides (J01XA); and other antibiotics.

In addition, we compared the prescription of narrow-spectrum and broad-spectrum antibiotics. We explored the definitions reported in previous studies on antibiotic classification and used an expert opinion panel including paediatric infectious disease specialists and general paediatricians (PERFORM partners), to establish the final classification into broad-spectrum and narrow-spectrum for all systemic antibiotics [5,6,11,15,27,28]. Narrow-spectrum antibiotics comprised penicillins (e.g., amoxicillin) and first-generation cephalosporins. Broad-spectrum antibiotics included penicillins with beta-lactamase inhibitor combinations (e.g., amoxicillin/clavulanic acid), macrolides, aminoglycosides, glycopeptides, and second-generation and third-generation cephalosporins. Prescriptions of both broad-spectrum and narrow-spectrum antibiotics in the same patient were considered broad-spectrum. Topical antibiotics were not included. Details of this classification are presented in S5 Text.

Outcomes

We assessed various aspects of antibiotic prescription: (1) antibiotic prescription rate; (2) the proportion of antibiotics that were broad-spectrum versus narrow-spectrum; (3) the proportion of antibiotics of ‘likely appropriate’ indication (presumed bacterial), ‘likely inappropriate’ indication (presumed viral), or ‘inconclusive’ indication (unknown bacterial/viral); (4) the proportion of oral antibiotics of inappropriate duration; and (5) the proportion of oral antibiotics that matched the antibiotic type in the local guideline (‘guideline-concordant’) in uncomplicated urinary and upper and lower RTIs. Antibiotic prescriptions were classified as likely appropriate in presumed bacterial infections (definite bacterial, probable bacterial, bacterial syndrome), likely inappropriate in presumed viral infections (definite viral, probable viral, viral syndrome), and inconclusive in unknown bacterial/viral infections or other infections. Inappropriate duration was defined as >10 days for treatment of tonsillitis with beta-lactamase sensitive penicillins (J01CE) and >7 days for all other prescriptions according to recommendations by international guidelines [2931]. In addition, guideline-concordant prescription in patients with uncomplicated RTIs and uncomplicated urinary tract infections was defined according to the local guideline (S6 Text). Uncomplicated infections were defined as infections in previously healthy children who did not receive therapeutic antibiotic treatment before the ED visit.

Data analysis

Missing values were assumed to be missing at random, and therefore we used multiple imputation by chained equations with the MICE package in R for the regression analysis. We excluded patients with missing data on antibiotic prescription, presumed cause of infection, and focus of infection [32]. Only the first visit was included for patients who visited the ED again within 5 days.

First, we performed a descriptive analysis of the frequency of antibiotic prescription and broad-spectrum and narrow-spectrum prescription, including ranges across EDs. For all outcomes, we calculated the overall proportion and proportion per ED. Second, we used multilevel logistic regression with a random intercept for each ED to study variation between EDs in antibiotic prescription, broad-spectrum prescription versus narrow-spectrum prescription, and intravenous/intramuscular versus oral prescriptions [33]. In an adjusted model we corrected for patient-level factors and for hospital-level factors influencing antibiotic prescribing. Patient-level factors were selected a priori according to the literature [3,4,23,34,35] and included general characteristics (age, sex, season, comorbidity, referral [referred versus self-referred]), markers for disease severity such as triage urgency (high urgency [immediate, very urgent, urgent] versus low urgency [standard, non-urgent]), fever duration in days, fever measured at ED visit (≥38°C), and presence of NICE guideline “red traffic light” alarming signs (0, 1, ≥2). We investigated diagnostics, including CRP (not performed or <20, 20–60, or >60 mg/l) [25,36], chest X-ray (not performed, normal, abnormal), and urinalysis (not performed, normal, abnormal [positive for leukocyte esterase and/or nitrite]). Furthermore, we included focus of infection (upper respiratory tract, lower respiratory tract, gastrointestinal, urinary tract, undifferentiated fever, skin/musculoskeletal, sepsis/central nervous system, flu-like illness/childhood exanthem, inflammatory/other) and diagnostic groups according to cause as classified by the flowchart in Fig 1: presumed bacterial (definite bacterial, probable bacterial, bacterial syndrome), unknown bacterial/viral, presumed viral (definite viral, probable viral, viral syndrome), and other.

For the hospital-level factors, we explored variables that varied between hospitals and were related to antibiotic prescribing [19,3740]: total number of ED visits, supervision, availability of point-of-care tests (streptococcal antigen test and CRP), and primary care during out-of-office hours. We included hospital-level factors if they improved the model using univariate analysis. Linearity of continuous variables was tested using restricted cubic splines. Specifications of the adjusted model are presented in Table 1 and in S7 Text.

Table 1. Variables in the adjusted model.

Category Variables
Patient-level factors
General characteristics Age*, sex, season, comorbidity, referral
Disease severity Triage urgency, fever duration, fever measured at ED, presence of NICE alarming signs, previous antibiotic use°
Diagnostics C-reactive protein, chest X-ray, urinalysis
Infection Focus of infection, cause of infection
Hospital-level factors± Total number of ED visits, supervision, availability of point-of-care tests (streptococcal antigen test and C-reactive protein), primary care during out-of-office hours±

*Age was modelled using restricted cubic splines (3 knots).

°Previous antibiotic use was added in the models with outcome broad-spectrum versus narrow-spectrum prescription.

±None of the hospital-level factors were significant, and therefore they were not included in the final model.

ED, emergency department; NICE, National Institute for Health and Care Excellence.

Variation in antibiotic prescription rates between EDs was determined by 2 measures: standardised prescription rates and median odds ratios (MORs). We calculated standardised antibiotic prescription rates using indirect standardisation, where the expected number of antibiotic prescriptions was standardised to the average ED. Standardised antibiotic prescription ratios are the ratio between observed antibiotic prescriptions in an ED and the expected antibiotic prescriptions in an ED. The expected number of antibiotic prescriptions was estimated through the adjusted model, by summing the predicted probabilities from the adjusted model of antibiotic prescription for each of the patients. Standardised rates > 1 indicate higher prescription rates than expected, and standardized rates < 1 indicate lower prescription rates than expected. We visualised standardised rates in a heat map.

The MOR is a measure of variation between high- and low-prescribing clusters of EDs. The MOR reflects the difference in probability of receiving antibiotics comparing similar patients attending an ED with high antibiotic prescribing and an ED with low antibiotic prescribing. If the MOR is equal to 1.00, there is no variation between clusters, and if the MOR is high, this indicates important between-cluster variation [41,42].

Stratified analyses were performed in patients with and without comorbidities. Also, since antimicrobial resistance patterns vary greatly between European countries, standardised rates of broad-spectrum versus narrow-spectrum antibiotic prescription were compared with antimicrobial resistance data of invasive isolates on a national level and at the hospital level [11,43] (S8 Text). Correlations were calculated using the 2-tailed Spearman’s rank coefficient (ρ). A p-value below 0.05 was considered significant.

Appropriateness of antibiotic prescriptions

We calculated standardised rates for antibiotic prescription and broad-spectrum prescription in groups of presumed viral infections, presumed bacterial infections, and unknown bacterial/viral infections. Next, we assessed the proportion of all antibiotic prescriptions that were likely appropriate, likely inappropriate, and inconclusive. For all oral prescriptions, we calculated the proportion of prescriptions that were both inappropriate in indication (likely inappropriate) and of inappropriate duration, and the proportion of prescriptions that were either inappropriate in indication or inappropriate in duration. In uncomplicated RTIs and urinary tract infections, we calculated the proportion of all oral prescriptions that were inappropriate for all the 3 measures (indication, duration, and guideline concordance), and the proportion of prescriptions that were inappropriate in any of the 3 measures. R version 3.4 was used for the analysis and visualisation of the data.

Results

Study population

Of the total population of 38,480 patients, we excluded 738 patients based on missing data of antibiotics or diagnosis, and the repeated visit of 2,092 patients to the same ED. Compared to patients with complete outcome data, patients with missing data were similar in age, sex, comorbidity, and admission rate (S9 Text). In addition, there were no differences in completeness of outcomes and diagnosis between discharged and admitted patients.

For the analysis, we included 35,650 febrile children (median age 2.8 years [IQR 1.3–5.6], 54.6% male). The different EDs varied substantially in patients who were referred (range: 4.9%–99.2%), were ill appearing (range: 0.8%–47.4%), or had any comorbidity (range: 5.1%–65.3%) (Table 2). The most common infections were upper respiratory tract (n = 18,783, 52.7%), lower respiratory tract (n = 5,167, 14.5%), gastrointestinal tract (n = 3,694, 10.4%), and undifferentiated fever (n = 2,784, 7.8%). The incidence of sepsis and central nervous system infections was low (n = 270, 0.8%). The majority of the children had a presumed viral infection (n = 20,383, 57.2%); presumed bacterial infections occurred in 22.1% of the patients (definite bacterial/bacterial syndrome, 4.1%; probable bacterial, 18.1%), and unknown bacterial/viral infections in 14.6% (n = 5,200) (Table 3).

Table 2. Patient characteristics of the study population (n = 35,650).

 Characteristic n (%) or median (IQR) Range across EDs (%) Missing, n (%)
Age in years 2.77 (1.32–5.59)
Male 19,476 (54.6) 51.5–59.1 1 (0.0)
Comorbidity 5,889 (16.5) 5.1–65.3 326 (0.9)
Season 1,111 (3.1)
    Winter 12,665 (35.5) 26.8–53.2
    Spring 9,054 (25.4) 18.2–31.2
    Summer 5,767 (16.2) 9.5–23.5
    Autumn 8,164 (22.9) 6.9–31.4
Triage urgency 1,059 (2.9)
    High: immediate, very urgent, urgent 12,251 (34.4) 8.3–88.5
    Low: standard, non-urgent 22,340 (62.7) 10.1–91.6
Referred 15,104 (42.4) 4.9–99.2 1,110 (3.1)
Fever duration in days 1.5 (0–3) 2,449 (6.9)
NICE “red traffic light” alarming signs
    Ill appearance 5,567 (15.6) 0.8–47.4 1,525 (4.3)
    Work of breathing 2,987 (8.4) 3.2–25.7 4,482 (12.6)
    Dehydration 1,763 (4.9) 0.4–15.2 6,323 (17.7)
    Rash: petechiae/non-blanching 1,039 (2.9) 1.4–5.8 3,963 (11.1)
    Decreased consciousness 188 (0.5) 0.1–3.8 334 (0.9)
    Meningeal signs 132 (0.4) 0.1–1.7 1,807 (5.1)
    Focal neurology 121 (0.3) 0.0–2.6 2,224 (6.2)
    Status epilepticus 60 (0.2) 0.0–1.9 1,099 (3.1)
C-reactive protein (CRP)
    No CRP performed 19,578 (54.9) 7.9–93.2
    <20 mg/l 8,729 (24.5) 3.2–58.4
    20–60 mg/l 4,191 (11.8) 1.9–24.9
    >60 mg/l 3,152 (8.8) 1.6–30.2
Chest X-ray
    No 30,662 (86.0) 78.6–93.8
    Normal 1,931 (5.4) 0.9–10.0
    Abnormal 3,057 (8.6) 2.9–12.8
Urinalysis
    No 26,691 (74.9) 60.8–91.4
    Normal 7,210 (20.2) 7.1–29.8
    Abnormal 1,749 (4.9) 1.5–9.5

ED, emergency department; IQR, interquartile range; NICE, National Institute for Health and Care Excellence.

Table 3. Patient characteristics of the study population: Outcomes, n = 35,650.

 Outcome n (%) or median (IQR) Range across EDs (%)
Therapeutic antibiotics use in last 7 days* 3,592 (10.1) 6.6–15.6
Antibiotic treatment duration, days 7 (5–10)
Antibiotics prescribed at ED visit or first day of hospital admission* 11,371 (31.9) 22.4–41.6
    Narrow-spectrum 5,401 (15.2) 3.1–23.2
    Broad-spectrum 5,887 (16.5) 9.5–34.7
Antibiotic administration*
    Oral 7,636 (21.4) 10.4–34.2
    Intravenous/intramuscular 3,564 (9.9) 1.7–21.3
Admission* 9,000 (25.2) 4.5–54.2
ICU admission* 147 (0.4) 0.1–4.3
Focus of infection
    Upper respiratory tract 18,783 (52.7) 25.7–70.0
    Lower respiratory tract 5,167 (14.5) 8.5–26.4
    Gastrointestinal/surgical abdomen 3,694 (10.4) 6.0–19.2
    Undifferentiated fever 2,784 (7.8) 1.8–18.8
    Flu-like illness/exanthem 1,753 (4.9) 2.0–11.9
    Urinary tract 1,231 (3.5) 1.2–5.8
    Soft tissue/musculoskeletal 876 (2.5) 0.5–6.8
    Sepsis/central nervous system 270 (0.8) 0.0–3.9
    Inflammatory 136 (0.4) 0.0–1.3
    Other 957 (2.7) 1.2–8.4
Cause of infection
    Presumed viral 20,383 (57.2) 37.3–71.4
    Definite bacterial 1,451 (4.1) 1.6–10.9
    Probable bacterial/bacterial syndrome 6,438 (18.1) 4.7–31.8
    Unknown bacterial/viral 5,200 (14.6) 1.6–37.9
    Other 2,178 (6.1) 1.1–30.9

*Missing: therapeutic antibiotic use in last 7 days, 681/35,650 (1.9%); antibiotic duration, 1,980/11,371 (17.4%); broad-spectrum versus narrow-spectrum antibiotics, 83/11,371 (0.7%); antibiotic administration, 171/11,371 (1.5%); admission and ICU admission, 25/35,650 (0.1%).

ED, emergency department; ICU, intensive care unit; IQR, interquartile range.

Overall antibiotic prescriptions

The overall antibiotic prescription rate was 31.9% (n = 11,371), of which 67.2% (7,636/11,731) were oral administrations and 31.3% (3,564/11,371) were administered intravenously or intramuscularly (153 children received a single dose at the ED). One-third of patients were treated with antibiotics for over 7 days (3,534/9,391, 37.6%) (S1 Fig). The types of antibiotics most often prescribed were penicillins with extended spectrum (3,220/11,371, 28.3%), combinations of penicillins with beta-lactamase inhibitors (2,309/11,371, 20.3%), and beta-lactamase sensitive penicillins (2,001/11,371, 17.6%). Half of the prescribed antibiotics were broad-spectrum agents (5,887/11,371, 51.7%). The most prescribed broad-spectrum antibiotics were combinations of penicillins with beta-lactamase inhibitors (2,309/11,371, 20.3%), second-generation cephalosporins (1,154/11,371, 10.1%), and third-generation cephalosporins (1,097/11,371, 9.6%) (Table 4; Fig 2).

Table 4. Frequencies of antibiotic classes and ranges across EDs (n = 11,371).

Antibiotic class n (%) Range across EDs (%)
Beta-lactamase sensitive penicillins (e.g., benzylpenicillin) 2,001 (17.6) 0.1–32.5
Beta-lactamase resistant penicillins (e.g., flucloxacillin) 167 (1.5) 0.0–8.1
Penicillins with extended spectrum (e.g., amoxicillin) 3,220 (28.3) 2.6–61.6
Combinations of penicillins with beta-lactamase inhibitors (e.g., amoxicillin with clavulanate) 2,309 (20.3) 1.4–59.0
Macrolides (e.g., azithromycin) 638 (5.6) 2.9–11.0
First-generation cephalosporins 167 (1.4) 0.0–9.8
Second-generation cephalosporins 1,154 (10.1) 0.0–25.6
Third-generation cephalosporins 1,097 (9.6) 1.1–25.1
Trimethoprim and sulphonamides 128 (1.1) 0.0–5.1
Aminoglycosides 205 (1.8) 0.0–15.6
Quinolones 51 (0.4) 0.0–2.8
Glycopeptides 31 (0.3) 0.0–2.7
Other 120 (1.1) 0.0–4.6
Missing 83 (0.7) 0.0–3.6

ED, emergency department.

Fig 2. Antibiotic classes of prescribed antibiotics across EDs, n = 35,650.

Fig 2

Red shades indicate broad-spectrum classes, blue shades indicate narrow-spectrum classes, and grey shades indicate unclassified classes and prescriptions of unknown class. EDs are sorted by antibiotic prescription rate. ED, emergency department; NL, the Netherlands; UK, United Kingdom.

Variation of overall antibiotic prescription and broad-spectrum prescription

The proportion of febrile children receiving an antibiotic prescription ranged from 22.4% to 41.6% across EDs, and the proportion of those prescriptions that were for broad-spectrum agents ranged from 33.0% to 90.3%. Of the broad-spectrum agents, penicillins with beta-lactamase inhibitors had the largest variation (range 1.4%–59.0%), but other broad-spectrum agents varied as well (range 17.3%–37.0%). Fig 3 presents the standardised prescription rates from the adjusted model. None of the hospital-level factors was related with antibiotic prescription (p-value range: 0.14–0.77). After correction for general patient characteristics (age, sex, season, comorbidity, referral), disease severity (triage urgency, fever duration, fever measured at ED, alarming signs), diagnostics, focus of infection, and cause of infection, variability of antibiotic prescriptions remained between EDs in the adjusted model (range of standardised prescription rates: 0.77–1.35; MOR 2.41). Variation was also observed for intravenous versus oral administration (range of standardised rates: 0.29–1.31; MOR 2.60) and prescription of broad-spectrum antibiotics versus narrow-spectrum antibiotics (range of standardised rates: 0.65–1.75; MOR 3.20). Stratified for comorbidity, standardised antibiotic prescription rates and broad-spectrum rates were comparable in children with and without comorbidity. Higher standardised rates for broad-spectrum antibiotics were not related to higher antimicrobial resistance percentages on a national level or on a hospital level (S8 Text). Results of variation of antibiotic and broad-spectrum prescriptions for RTIs are provided in S10 Text.

Fig 3. Heat map of standardised prescription rates by ED (95% CI).

Fig 3

All adjusted for age, sex, season, comorbidity, referral, triage urgency, fever measured at ED, fever duration, alarming signs, CRP, chest X-ray, urinalysis, focus of infection, and cause of infection. EDs are ordered according to standardised antibiotic prescribing rate, from low to high on the left vertical axis. The coloured boxes represent rank of standardised rate for each ED: Red indicates rates > 1, blue indicates rates < 1, and rates equal to 1 are white. *Also adjusted for previous antibiotic use. ED, emergency department; NL, the Netherlands; UK, United Kingdom.

Variation of antibiotic and broad-spectrum prescriptions in viral infections, bacterial infections, and unknown bacterial/viral infections

The antibiotic prescription rate was 6.9% (1,418/20,383) for presumed viral infections (range across EDs: 0.4%–18.9%), 88.8% (1,289/1,451) for definite bacterial infections (range across EDs: 83.5%–96.2%), 94.7% (6,097/6,438) for probable bacterial/bacterial syndrome infections (range across EDs: 81.2%–99.3%), and 45.2% (2,348/5,200) for unknown bacterial/viral infections (range across EDs: 1.7%–79.3%) (S2 Fig).

Adjusted for general characteristics, disease severity, diagnostics, and focus of infection, we observed variation for antibiotic prescriptions in presumed viral infections (range of standardised rates: 0.05–3.29; MOR 4.91) and unknown bacterial/viral infections (range of standardised rates: 0.05–1.78; MOR 4.78) (Fig 4). Antibiotic prescriptions varied less for patients with presumed bacterial infections (range of standardised rates: 0.91–1.06; MOR 2.32). The proportion of broad-spectrum prescriptions was 74.1% (1,037/1,399) for presumed viral infections (range across EDs: 38.9%–91.4%), 68.5% (880/1,284) for definite bacterial infections (range across EDs: 39.2%–96.0%), 43.2% for probable bacterial/bacterial syndrome infections (2,628/6,081, range across EDs: 28.5%–86.3%), and 51.6% (1,191/2,306) for unknown bacterial/viral infections (range across EDs: 20.0%–95.7%) (S2 Fig). After adjustment, differences for broad-spectrum versus narrow-spectrum antibiotics remained for presumed viral infections (range of standardised rates: 0.57–1.54; MOR 2.59), presumed bacterial infections (range of standardised rates: 0.66–1.86; MOR 3.09), and unknown bacterial/viral infections (range of standardised rates: 0.44–1.64; MOR 3.70) (S3 Fig).

Fig 4. Heat map of standardised antibiotic prescription rates by ED for presumed viral, presumed bacterial, and unknown bacterial/viral infections (95% CI).

Fig 4

All adjusted for age, sex, season, comorbidity, referral, triage urgency, fever duration, alarming signs, CRP, chest X-ray, urinalysis, and focus of infection. EDs are ordered according to standardised antibiotic prescribing rate, from low to high on the left vertical axis. The coloured boxes represent rank of standardised rate for each ED: Red indicates rates > 1, blue indicates rates < 1, and rates equal to 1 are white. ED, emergency department; NL, the Netherlands; UK, United Kingdom.

Variation in prescriptions of appropriate indication and appropriate duration

Of all antibiotic prescriptions, 65.0% (7,386/11,371) were determined to be likely appropriate (range across EDs: 23.7%–98.9%), 12.5% (1,418/11,371) were likely inappropriate (range across EDs: 0.6%–29.3%), and 22.6% (2,567/11,371) were inconclusive (range across EDs: 0.5%–61.7%).

Oral antibiotic prescriptions with inappropriate duration were found in 20.0% (1,525/7,636) of prescriptions, and this ranged from 4.4% to 59.0% across EDs (Fig 5). Of all oral antibiotic prescriptions, 2.1% (134/7,636) were of both inappropriate indication and inappropriate duration (range across EDs: 0.0%–8.4%), whereas 30.0% (2,294/7,636) were either of inappropriate indication or of inappropriate duration (range across EDs: 11.3%–69.9%).

Fig 5. Heat map of inappropriateness of antibiotic prescriptions across EDs.

Fig 5

EDs are ordered according to proportion of inappropriately indicated prescriptions, from low to high on the left vertical axis. The coloured boxes represent rank of proportion for each ED: Red indicates the highest proportion, and white indicates the lowest proportion. ED, emergency department; NL, the Netherlands; UK, United Kingdom.

Variation of appropriate prescriptions in uncomplicated RTIs and urinary tract infections

In uncomplicated RTIs, oral prescriptions were not guideline-concordant in 22.3% (973/4,373) of prescriptions (range across EDs: 11.8%–47.3%) (Fig 5). In this group, the proportion of prescriptions that were inappropriate in all 3 measures (indication, duration, and guideline concordance) was 0.7% (31/4,373), whilst 42.3% (1,850/4,373) were inappropriate in any of the 3 measures (range across EDs: 15.7%–80.9%). In uncomplicated urinary tract infections, oral prescriptions were not concordant with the local guideline in 45.1% of prescriptions (152/337) (range across EDs: 11.1%–100%), and 65.9% (222/337) were inappropriate in any of the 3 measures (range across EDs: 11.1%–100%).

Discussion

In this large prospective multicentre study, we found diversity in antibiotic prescriptions, and in particular broad-spectrum antibiotic prescriptions, for febrile children attending different EDs in Europe. After adjustment for general characteristics, disease severity, diagnostics, and focus of infection, we observed minor variation in antibiotic prescriptions for bacterial infections, and larger variability in antibiotic prescriptions for viral infections and unknown bacterial/viral infections. Moreover, one-third of all antibiotic prescriptions were of inappropriate or inconclusive indication, and 20% of oral prescriptions were of inappropriate duration, with large variation across EDs. Between EDs, the proportion of oral prescriptions that were not concordant with the local guideline varied from 12% to 47% in RTIs and from 11% to 100% in urinary tract infections.

Our study supports previous studies that reported variable antibiotic prescribing for all febrile children, but found less variation than a previous study in children with RTIs across 28 European EDs (range of standardised rates: 0.5–2.0) [5]. In contrast to this study, our study corrected for aetiology of infection—bacterial, viral, or unknown—based on a standardised flowchart. Studies in the US on diversity in outpatient antibiotic prescribing found regional differences in both antibiotic and broad-spectrum prescribing [6,10,17]. These studies, however, were not focused on ED visits alone since all ambulatory visits were included.

The Access, Watch, and Reserve (AWaRE) classification has recently been used to classify global antibiotic prescriptions in 2 studies assessing oral formulations and use of inpatient antibiotics in children [14,44,45]. These studies confirmed variable patterns of antibiotic prescribing between countries, but did not adjust for differences in population and did not report data of emergency care visits. Further, the AWaRE classification led to a substantial proportion of unclassified antibiotics in our study population (12.2%; range across EDs: 1.9%–26.9%) and absence of the reserve category.

Previous studies in the US have evaluated appropriateness of antibiotic prescribing in children defined by ICD codes. Poole et al. [46] found that prescriptions were in general not indicated in 32% of emergency care visits in children. Additionally, overall prescription of first-line antibiotics (amoxicillin, amoxicillin-clavulanate) ranged from 50% to 78% for RTIs in children [4648]. We found a similar rate of guideline-concordant prescriptions in RTIs (78%), whilst guideline concordance was defined differently for most EDs: amoxicillin and narrow-spectrum penicillins according to the local guideline. One ED (UK, 3) used amoxicillin-clavulanate as first-line for RTIs. Our study is the first to our knowledge to evaluate appropriateness of antibiotic prescribing in febrile children visiting different EDs in Europe, using a structured flowchart categorising viral, bacterial, and unclassified infections, and taking local guidelines into account.

Strengths of this European multicentre study include the large sample size, detailed patient information, recruitment in a diverse range of ED settings in 8 EU countries, and recruitment over a full year to reflect seasonal variation. Furthermore, a rigorous, standardised structured assessment of all cases was carried out to establish the presumed cause of infection, using a consensus-based flowchart taking into account clinical syndrome, CRP, and culture results. Previous studies have addressed appropriate prescribing for diagnoses based on ICD codes. This classification, however, may not accurately take into account bacterial or viral aetiology [6,10,17,46]. Our large sample size enabled adjustment for hospital- and patient-level factors influencing antibiotic use in the EDs [19].

This study has some limitations. First, the included EDs are not representative of all febrile children attending the ED in that country. The EDs participating in this study are university hospitals or large teaching centres with intensive care unit facilities involved in paediatric infectious disease research collaborations. Fever and sepsis guidelines were available in all EDs [19]. Therefore, these EDs represent a high standard of care, and generalisation of our findings to smaller hospitals or to a regional or national level should be undertaken with caution. However, we corrected for the most important confounders including comorbidities, multiple markers of disease severity, and focus and presumed cause of infection. Second, although the experience of the physician (resident or consultant) and clinician specialty are related with antibiotic prescription [49,50], we could not adjust for physician background at the patient level. However, we evaluated the contribution of supervision to antibiotic prescription at the hospital level. In our study, supervision was not related to antibiotic prescription. Our efforts to improve data quality by training clinical and research staff might have influenced common clinical practice. Since this training focused on awareness of alarming signs in the clinical assessment of the febrile child, it is unlikely that it influenced antibiotic prescription. Furthermore, we only included the first visit of patients who repeatedly visited the ED, since data collection did not include secondary visits in all EDs.

Differences in antibiotic prescribing could be influenced by differences in immunisation coverage. In our study, countries with lower coverage for pneumococcal vaccinations (<90%) (Germany, Slovenia) did not have higher antibiotic prescriptions at the ED [19,51].

We found large variation in broad-spectrum prescriptions across the different EDs. Increased antimicrobial resistance rates could possibly explain higher broad-spectrum prescribing. We compared broad-spectrum rates with national data for antimicrobial resistance and hospital methicillin resistance rates. Interestingly, EDs based in countries with higher antimicrobial resistance on a population level (e.g., Greece, Spain) prescribed less broad-spectrum agents than expected in the ED. These hospitals with higher burden of national antimicrobial resistance may perceive more problems with antimicrobial resistance and might feel a greater pressure to reduce antibiotic prescriptions in the ED. It should be noted that antibiotic prescribing in the ED will not be representative of antibiotic prescription patterns of primary care in the community.

The diversity in antibiotic prescribing across different EDs appears not to be associated with antimicrobial resistance or immunisation coverage. Although the ideal antibiotic prescription rate is unknown, the diversity in antibiotic prescribing suggests overprescribing. Prescription rates were above the average incidence of serious bacterial infections. We found variation in antibiotic prescription rates, even when adjusting for general characteristics, disease severity, diagnostics, and focus and cause of infection.

This suggests room for improvement in reduction of antibiotic prescriptions and especially broad-spectrum prescriptions at the ED. EDs with higher antibiotic prescription rates did not necessarily prescribe more broad-spectrum antibiotics. The ED with the highest standardised broad-spectrum rate (UK, 3) did not have a high proportion of inappropriate prescriptions for RTIs. In only this ED, amoxicillin-clavulanate (broad-spectrum) was the first-choice agent for uncomplicated RTIs, which could explain the higher broad-spectrum rate in this ED. Studies demonstrated that use of narrow-spectrum antibiotics compared to broad-spectrum antibiotics leads to similar clinical outcomes and to fewer adverse events [28,52]. Unnecessary use of broad-spectrum antibiotics potentially increases resistance rates even further.

In addition, diversity of antibiotic prescription increased with diagnostic uncertainty. After adjustment for general characteristics, disease severity, diagnostics, and focus of infection, we observed minor variation in antibiotic prescriptions for bacterial infections, and larger variability in antibiotic prescriptions for viral infections and unknown bacterial/viral infections. In general, EDs with higher antibiotic prescription rates in viral infections also had higher antibiotic prescription rates in unknown bacterial/viral infections. This indicates that overprescribing in viral infections is linked to higher prescriptions in unknown bacterial/viral infections. Diagnostic uncertainty in patients with an unclear cause of infection could be reduced by improved targeted antibiotic prescription from new diagnostic signatures of bacterial and viral infection.

We evaluated appropriateness in indication, duration, and guideline concordance. Ideally, EDs should target 100% appropriateness in these 3 aspects of antibiotic prescribing. In our study, we did not observe a clear association between inappropriately indicated prescriptions and prescriptions of inappropriate duration. This indicates that guideline implementations should focus on these different aspects of appropriate antibiotic prescribing to ensure prescriptions of appropriate indication, duration, and antibiotic selection. Furthermore, quality improvement initiatives should be emphasised in EDs with higher proportions of inappropriate prescriptions. In addition, future antimicrobial stewardship interventions across Europe should focus on reducing broad-spectrum treatment and antibiotic use in viral infections.

To conclude, we found substantial variation in antibiotic prescriptions and especially broad-spectrum antibiotic prescriptions in European EDs after adjustment for patient characteristics, disease severity, diagnostics, and focus and cause of infection. The proportion of antibiotic prescriptions in bacterial infections was comparable between EDs, but diversity was especially large in antibiotic prescriptions for viral infections and unknown viral/bacterial infections. This variation indicates overprescription of antibiotics in these groups of patients. Furthermore, indications of prescriptions were inappropriate or inconclusive in one-third of prescriptions, and this proportion varied between EDs. In respiratory and urinary infections, guideline concordance of prescriptions varied widely across EDs. Until better diagnostics are available to accurately differentiate between bacterial and viral aetiologies, we strongly urge the implementation of antimicrobial stewardship guidelines to reduce antibiotic prescription in febrile children across Europe.

Supporting information

S1 Fig. Duration of prescribed antibiotics.

(PDF)

S2 Fig. Range of antibiotic prescriptions and broad-spectrum prescriptions by emergency department (ED) for viral, bacterial, and unknown bacterial/viral infections.

(A) antibiotic prescriptions; (B) broad-spectrum prescriptions.

(PDF)

S3 Fig. Heat map of standardised broad-spectrum versus narrow-spectrum rates for viral, bacterial, or unknown bacterial/viral infections.

(PDF)

S1 Text. STROBE checklist.

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S2 Text. Statistical analysis plan.

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S3 Text. Ethics committees of participating hospitals.

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S4 Text. Hospital characteristics.

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S5 Text. Broad-spectrum and narrow-spectrum antibiotic definitions.

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S6 Text. Local guidelines of antibiotic treatment.

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S7 Text. Details of the adjusted model.

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S8 Text. National and hospital antimicrobial resistance data.

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S9 Text. Descriptive characteristics of cases with complete outcomes and cases with missing outcomes.

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S10 Text. Variation of antibiotic and broad-spectrum prescription in lower RTIs and otitis media, tonsillitis/pharyngitis, and other upper RTIs.

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S11 Text. PERFORM consortium.

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Acknowledgments

We acknowledge all research nurses for their help in collecting data, and Anda Nagle (Riga) and the Institute of Microbiology at University Medical Centre Ljubljana for their help in collecting data on antimicrobial resistance. Members of the PERFORM consortium are listed in S11 Text.

Abbreviations

CRP

C-reactive protein

ED

emergency department

MOR

median odds ratio

RTI

respiratory tract infection

Data Availability

An anonymized data set containing individual participant data is available in a public data repository: https://data.hpc.imperial.ac.uk/resolve/?doi=7251. DOI: 10.14469/hpc/7251. For inquiries to obtain the full dataset, please contact the data manager of the PERFORM consortium (Tisham.de08@imperial.ac.uk).

Funding Statement

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 668303. The Research was supported by the National Institute for Health Research Biomedical Research Centres at Imperial College London, Newcastle Hospitals NHS Foundation Trust and Newcastle University. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. For the remaining authors no sources of funding were declared. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

Louise Gaynor-Brook

13 Jan 2020

Dear Dr. Moll,

Thank you very much for submitting your manuscript "Variation in antibiotic prescription rates in febrile children presenting to Emergency Departments across Europe: PERFORM, an observational multicentre study" (PMEDICINE-D-19-04008) for consideration at PLOS Medicine.

Your paper was evaluated by a senior editor, discussed with an academic editor with relevant expertise, and sent to independent reviewers, including a statistical reviewer. The reviews are appended at the bottom of this email and any accompanying reviewer attachments can be seen via the link below:

[LINK]

In light of these reviews, I am afraid that we will not be able to accept the manuscript for publication in the journal in its current form, but we would like to consider a revised version that addresses the reviewers' and editors' comments. Obviously we cannot make any decision about publication until we have seen the revised manuscript and your response, and we plan to seek re-review by one or more of the reviewers.

In revising the manuscript for further consideration, your revisions should address the specific points made by each reviewer and the editors. Please also check the guidelines for revised papers at http://journals.plos.org/plosmedicine/s/revising-your-manuscript for any that apply to your paper. In your rebuttal letter you should indicate your response to the reviewers' and editors' comments, the changes you have made in the manuscript, and include either an excerpt of the revised text or the location (eg: page and line number) where each change can be found. Please submit a clean version of the paper as the main article file; a version with changes marked should be uploaded as a marked up manuscript.

In addition, we request that you upload any figures associated with your paper as individual TIF or EPS files with 300dpi resolution at resubmission; please read our figure guidelines for more information on our requirements: http://journals.plos.org/plosmedicine/s/figures. While revising your submission, please upload your figure files to the PACE digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at PLOSMedicine@plos.org.

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We ask every co-author listed on the manuscript to fill in a contributing author statement, making sure to declare all competing interests. If any of the co-authors have not filled in the statement, we will remind them to do so when the paper is revised. If all statements are not completed in a timely fashion this could hold up the re-review process. If new competing interests are declared later in the revision process, this may also hold up the submission. Should there be a problem getting one of your co-authors to fill in a statement we will be in contact. YOU MUST NOT ADD OR REMOVE AUTHORS UNLESS YOU HAVE ALERTED THE EDITOR HANDLING THE MANUSCRIPT TO THE CHANGE AND THEY SPECIFICALLY HAVE AGREED TO IT. You can see our competing interests policy here: http://journals.plos.org/plosmedicine/s/competing-interests.

Please use the following link to submit the revised manuscript:

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Your article can be found in the "Submissions Needing Revision" folder.

To enhance the reproducibility of your results, we recommend that you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see http://journals.plos.org/plosmedicine/s/submission-guidelines#loc-methods.

Please ensure that the paper adheres to the PLOS Data Availability Policy (see http://journals.plos.org/plosmedicine/s/data-availability), which requires that all data underlying the study's findings be provided in a repository or as Supporting Information. For data residing with a third party, authors are required to provide instructions with contact information for obtaining the data. PLOS journals do not allow statements supported by "data not shown" or "unpublished results." For such statements, authors must provide supporting data or cite public sources that include it.

We look forward to receiving your revised manuscript.

Sincerely,

Louise Gaynor-Brook, MBBS PhD

Associate Editor

PLOS Medicine

plosmedicine.org

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Requests from the editors:

General comments: Please replace ‘gender’ with ‘sex’ throughout the manuscript

Please position reference brackets before any punctuation (comma or full stop), separated by a space.

Please revise your title according to PLOS Medicine's style. We suggest “Variation in antibiotic prescription rates in febrile children presenting to Emergency Departments across Europe (PERFORM): a multicentre observational study”

Data Availability: PLOS Medicine requires that the de-identified data underlying the specific results in a published article be made available, without restrictions on access, in a public repository or as Supporting Information at the time of article publication, provided it is legal and ethical to do so. Please see the policy at http://journals.plos.org/plosmedicine/s/data-availability and FAQs at

http://journals.plos.org/plosmedicine/s/data-availability#loc-faqs-for-data-policy

If the data are not freely available, please describe briefly the ethical, legal, or contractual restriction that prevents you from sharing it. Please also include an appropriate contact (web or email address) for inquiries (please note that this cannot be a study author).

Abstract Background: Provide expand upon the context of why the study is important. The final sentence should clearly state the study question. Please define ‘PERFORM’

Abstract Methods and Findings:

Please provide more detail on the setting (e.g. which European countries, types of hospital) and brief demographic details on the study population (e.g. age, sex)

In the last sentence of the Abstract Methods and Findings section, please describe the main limitation(s) of the study's methodology.

Please begin your Abstract Conclusions with "In this study, we observed ..." or similar.

Please interpret the study based on the results presented in the abstract, emphasizing what is new.

At this stage, we ask that you include a short, non-technical Author Summary of your research to make findings accessible to a wide audience that includes both scientists and non-scientists. The Author Summary should immediately follow the Abstract in your revised manuscript. This text is subject to editorial change and should be distinct from the scientific abstract. Please see our author guidelines for more information: https://journals.plos.org/plosmedicine/s/revising-your-manuscript#loc-author-summary

Please expand upon your Introduction to address past research and explain the need for and potential importance of your study. Indicate whether your study is novel and how you determined that. If there has been a systematic review of the evidence related to your study (or you have conducted one), please refer to and reference that review and indicate whether it supports the need for your study.

Line 123 - please correct ‘ED’s’ to ‘EDs’

Methods

Thank you providing a STROBE checklist. Please add the following statement, or similar, to the Methods: "This study is reported as per the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline (S1 Checklist)." When completing the checklist, please use section and paragraph numbers, rather than page numbers.

Did your study have a prospective protocol or analysis plan? Please state this (either way) early in the Methods section. If a prospective analysis plan was used in designing the study, please include the relevant prospectively written document with your revised manuscript as a Supporting Information file to be published alongside your study, and cite it in the Methods section. A legend for this file should be included at the end of your manuscript. If no such document exists, please make sure that the Methods section transparently describes when analyses were planned, and when/why any data-driven changes to analyses took place.

Results

Throughout your results, please indicate what the results in brackets represent (mean? and range)

Line 326-328: Please provide 95% CIs and p values

Lines 337 & 443 - Please indicate which factors are adjusted for

Line 356 - please clarify what is meant by ‘prescription rates remained’

Line 359 - please correct to ‘upper respiratory tract infection’

At line 374, you describe the study as a "large prospective multicentre study". It may be that the study reports a retrospective analysis of prospectively collected data, and we ask you to adapt the language as appropriate.

Discussion

Please remove subheadings within the Discussion section

Please present and organize the Discussion as follows: a short, clear summary of the article's findings; what the study adds to existing research and where and why the results may differ from previous research; strengths and limitations of the study; implications and next steps for research, clinical practice, and/or public policy; one-paragraph conclusion.

References

Please ensure that journal titles are appropriately formatted and capitalised e.g. ref 7 BMJ; ref 22 JAMA; ref 43 formatting issues

Please add additional access details to reference 16.

Can the title of reference 43 be translated?

Supplementary Files

S2 Appendix - ‘investigation’ is misspelt in the the figure

S3 Appendix - please correct ref 5

Comments from the reviewers:

Reviewer #1: This descriptive, cross-sectional study documents widespread variation in antibiotic prescribing among 12 European emergency departments to children who either present with fever or had a recent history of fever. The authors find widespread variation in prescribing particularly for viral conditions or conditions in which the etiology is either viral of bacterial.

The authors have collected a large, rich, and impressive set of clinical data - by far the greatest strength of this paper. Moreover, there is no question that antibiotic stewardship in the ED for children is of utmost importance. The manuscript is generally easy to follow and the figures are helpful, particularly the Appendix figure with a flow chart with how the various categories like "presumed bacterial" were defined.

Despite these strengths, my major concern is that the research question the authors have asked - i.e., what is the degree of variation in antibiotic prescribing among these 12 European EDs - seems like the least interesting question they could have addressed using their impressive data. Based on the way it is framed, this study runs the risk of being seen as another paper documenting variation in care among some defined group of units (in this case, EDs). The weaknesses of such papers are 1) So many similar papers have been published that the only truly shocking finding would be the LACK of variation in care; and 2) It is difficult to know exactly to know what to do when variation is demonstrated, as the "appropriate" amount of variation is unknown even when you can adjust for the rich set of clinical variables that the authors have access to. This is the Achilles heel of variations-based analyses - at best, they can hint at potential overuse of care (in this case, antibiotics).

Some of the more important questions that could have been asked with these rich data include:

1) Why is there so much apparent over-testing? 45% of the children received a CRP - perhaps this is just a trans-Atlantic difference, but CRP is not routinely obtained for febrile children in the ED in the U.S., nor is it viewed as a particularly useful discriminator between viral and bacterial infections. Similarly, 25% of children received a urinalysis, but the focus of infection was the urinary tract for just 3.5% of children. These numbers boggle my mind.

2) What is the estimated rate of antibiotic overuse? The authors could devise a system, for example, in which they consider antibiotics to be likely inappropriate if the patient had a confirmed or probable viral infection; likely appropriate if there was a confirmed or probable bacterial infection; and possibly appropriate for everything else. They could use their rich data on lab results, CXR results, and diagnoses to further their classification scheme. They could then perhaps utilize the variation between EDs to establish achievable benchmarks of prescribing for the "possibly appropriate" category (e.g., the 20th percentile of prescribing).

3) Given that the authors presumably have data on prescription duration and whether the agent was broad spectrum vs not, they could go even further and classify not just whether the indication was antibiotic-appropriate or not, but also whether the duration and choice of antibiotic were appropriate. They could calculate the proportion of antibiotics prescribed that had any deficit (inappropriate indication, inappropriate duration, inappropriate agent). These are questions that are really difficult to answer using the administrative datasets that most studies of antibiotic prescribing rely on.

My point is simply that demonstrating variation alone does not move the needle very much, because there will always be variation. It is simply a shame in my mind to use the amazing data the authors have collected simply to document the existence of variation.

Other issues

1) Why focus only on children with fever or a history of fever? Many antibiotics are inappropriately written to children to afebrile children with, say, a 10-day course of non-improving cough.

2) The authors say that they ran a multilevel logistic regression model with clustering on the hospitals. Those two terms don't go together - one typically can either regarding clustering as a nuisance and adjust for it (e.g., generalized estimating equations) vs view the variation between clusters as being of primary interest (multilevel model). I'm pretty sure what the authors did is run a multilevel logistic model with a random hospital intercept (different from clustering on hospital)", but this should be clarified.

3) I can't tell if this is in the model or not, but one of the patient-level predictors should be current fever in the ED vs no fever but positive history - clinicians are definitely more likely to prescribe antibiotics if the child has a fever in the ED. On that note, please write out the regression model - it is not clear from the text what variables are included or not.

4) I think it would be more sensible to restrict the sample only to treat-and-release ED patients - examining antibiotics started in the ED for hospitalized patients seems a bit odd.

Reviewer #2: Thank you for the opportunity to read and review with interest the results of the PERFORM study, a multi-centre observational study describing antibiotic prescribing rates for children < 18 years across several large teaching hospitals in Europe. The study is largely descriptive in nature, quantifying variation in prescribing across hospital centres, and describing the nature of the prescribing behaviour (by type) and consideration of patient and hospital factors which be associated with prescribing rates. The results are topical as growing antibiotic resistance is a continuing problem in many health care systems and reports such as these are very helpful is quantifying the scale of the issue. I have a few comments in regards to mostly the methodology and some suggestions which the authors may want to consider:

To help improve clarity in abstract reporting:

1) Methods - when describing primary outcomes, it is unclear what the denominator is in the rates and what type of unit of measurement this is: i.e. general prevalence as a %, per specific number. Please include how prescription rate is defined in the abstract.

2) Findings - "after standardisation" - It would be helpful to describe how rates were standardisation as there are several different methods of standardisation rates (i.e. direct/indirect)

3) Findings Line 92 - The abstracts reads as if broad and narrow spectrum antibiotics were supposed to be compared but the authors seem to report range combined. Please clarify

4) General comment on abstract findings reporting - Could the authors comment what constitutes descriptors such as "considerable variation", "varied substantially", and "little variation" as there is no a priori definition of this or explanation. I would generally favour refraining from using these adjectives without defining the range differences. For instance, in the results sections, the focus should be on just simply presenting the results (i.e "the range was: "). Instead, the qualitative interpretation of what constitutes "considerable", "little", variation should be provided in the context of the discussion. Alternatively, the authors wish to do this, they should define range definitions in the methods section.

In the main text:

5) Lines 151-152: This is quite important process of the study design - that was active data collection during the study period with training of research staff on data collection and clinical assessment. Hence, you could even argue there is an interventional component to this analyses and not purely an "observational" study. Whilst I recognise the rationale for this is to improve data capture and quality - the authors primary limitation is further amplified - that these hospitals may not necessary generalise because of this reason. What would have enhanced this would have been to have a pure retrospective one-year look-back period prior to the study active data collection taken place. Whilst it may not possible to do this, it is worth mentioning commenting in the discussion.

6) Lines 154: I'm am quite puzzled by the sample size justification. The rule-of-thumb of 10 events per variable sample size calculation generally is used as a justification for developing prognostic models. Besides the 10 EPV rule-of-thumb being outdated for prognostic models (see Riley et al. - https://onlinelibrary.wiley.com/doi/full/10.1002/sim.7992), the author applied a multi-level model which means a design effect needs to accounted for (i.e. ICC between hospitals). Further, this study is also not testing a particular hypothesis as purely observational (primary outcome is simply a prescription rate) - so why not just determine the sample size based on the expected/desired precision on the prescribing rates?

7) Lines 224: How many children were excluded with missing data on antibiotic use, presumed cause of infection, and focus of infection and did their characteristics differ from those who were included. It would be good to show if these children were similar or different to the analysis cohort

8) Lines 225-226: What was the rationale for including only the first visit for patients within the first five days? Is there any risk of under-ascertainment of prescribing rates if the initial visit did not include any prescribing but it subsequently occurred at subsequent visits?

9) Lines 229: Use of multi-level logistic regression model needs some justification. For prescribing rates, you could also argue that a Poisson regression model and then incorporate patient level covariates in the model. This would essentially derive your rate over the period of time of data collection as well.

10) Lines 230-231: How were patient level factors selected for inclusion in the model. By a priori specification or was there any covariate testing for interaction and confounding. Please describe.

11) Lines 250-251: The standardisation process, what was the reference population used to obtain the expected antibiotic prescribing and where was this data obtained from?

12) Lines 260-265: How did the authors define categories of "high" and "low" for their heat maps. What this based on evidence or consensus (i.e. planned analysis, post-hoc consensus). If would be useful to see the pre-specified analytical plan (if there was any) and if there wasn't, this also needs to be mentioned and commented in the discussion as a potential limitation.

13) Table 1, Final diagnosis is interesting as most look majority are labelled probable viral (57.2%), where definite bacterial only (4.1%) and probable bacterial is 18.1%. It would be useful if the authors could provide a metric of inappropriate or appropriate prescribing. This would require essentially mapping the prescription to the final diagnoses. This analysis stratified by hospital would be useful as Figure 3 shows the three UK hospital having the hospitals having the high rates of prescribing, but at the moment it's not conclusive whether high prescribing was due to having more patients with particular types of diagnoses.

14) Lines 325: Could this be due to the appropriateness of the prescribing. Can the authors comment on this?

Reviewer #3: This is a large prospective, multicenter observational study that assesses antibiotic prescription in children in 12 European EDs. Data collection was mostly based on routine clinical data, which makes this study particularly interesting. Since adequate disease classification for pediatric infectious diseases is not available for pediatric patients, the authors undertook the effort of classifying the likely etiology of infection. This study in an important first step towards more systematic data collection on antibiotic prescription in European ambulatory settings and provides important data on variability of antibiotic prescription practices. The authors should be congratulated on this important effort. The present manuscript focuses on patient-related factors to describe variations in the prescription rates observed. The manuscript would be greatly strengthened by taking more provider, health systems and data quality issues into account (or to at least give the reader a sense to which extent these were taken into consideration). Specifically, the following points should be addressed further:

* This study relied on routine data collection. EDs are busy places with high staff turnover. I imagine that the EMR system varies a lot from hospital to hospital, as does the type and quality of routine medical documentation. One would like a better sense on how data was extracted from routine data sources and how the quality of this data was assessed? What are the influencing factors for data quality and completeness? The authors also mention that enumerators were trained in a CRF. I assume that not all routine providers were trained in data collection procedures for this study? How was the data extracted from the routine medical record system into the eCRF? How are antibiotic prescriptions recorded at the different sites? Are there differences in the completeness/ type of documentation between ambulatory and admitted patients? In some countries, for example, DRGs are implemented for admitted patients resulting in differential documentation for hospitalized patients due to billing issues.

* What are provider-related factors that influence prescription between sites (type of provider, level of training)? Please represent in your data analysis.

* I imagine that antibiotic prescription is largely related to local/national guidelines. For example, nitrofurantoine is specifically not recommended as first line for UTIs in some countries to spare the antibiotic; and TMP/SULFA is recommended as a first line instead. How was this assessed in the study? Could you add an analysis: per guideline/ not per guideline?

* What are health-system related factors beyond guidelines that drive antibiotic prescription? Which ones were assessed/ not assessed?

* I understand how the classification of antibiotics into narrow versus broad was reached; however, it is certainly disputable in some instances (e.g. pipercillin =narrow, cefuroxim=broad). Could you provide some

Furthermore, a better sense of the generalizability of the data should be provided. How was the site selection performed? How does it relate to national averages in key institutional/ health system aspects?

Are you looking at use or prescriptions? Two different concepts that are measured differently. Please clarify across the manuscript.

Additional Minor Comments

* L113: the IQR appears out of context here. Specify

* Introduction: give short introduction to PERFORM project

* AIM: reformulate aim to align with your analysis. I think you would want to say: variations in rate and types of antibiotic prescription

Methods

* How were the participating hospitals selected?

* Are these pediatric EDs? Who sees patients? GPs? Pediatricians? Emergency Medicine Specialists?

* How was duration of data collection determined?

* The rationale for your sample size calculation is unclear to me; please expand. Comment on generalizability

* Does the missing at random assumption really hold here (for example various NICE traffic light factors are related amongst each other)? How did you decide on this?

* Did you exclude patients with missing data on antibiotic use or antibiotic prescription?

* How did you account for the difference in triage systems to account for "triage level"?

* "Second, we used multilevel logistic regression using clustering on hospital to study variation of antibiotic use between hospitals". This is unclear to me: if you introduce hospital as a random effect (clustering), you would not be able to compare between hospitals?

* How did you decide on the CRP cutoffs? Based on what?

Results

* Table 1: the range of patients classified under the triage category seems very wide. How is this explained?

* L 359: remained…. Is there a word missing?

* Fog 5/6: heat map of what?

Any attachments provided with reviews can be seen via the following link:

[LINK]

Decision Letter 1

Thomas J McBride

31 May 2020

Dear Dr. Moll,

Thank you very much for re-submitting your manuscript "Variation in antibiotic prescription rates in febrile children presenting to Emergency Departments across Europe (PERFORM): a multicentre observational study" (PMEDICINE-D-19-04008R1) for review by PLOS Medicine.

I have discussed the paper with my colleagues and the academic editor and it was also seen again by two reviewers. I am pleased to say that provided the remaining editorial and production issues are dealt with we are planning to accept the paper for publication in the journal.

The remaining issues that need to be addressed are listed at the end of this email. Any accompanying reviewer attachments can be seen via the link below. Please take these into account before resubmitting your manuscript:

[LINK]

Our publications team (plosmedicine@plos.org) will be in touch shortly about the production requirements for your paper, and the link and deadline for resubmission. DO NOT RESUBMIT BEFORE YOU'VE RECEIVED THE PRODUCTION REQUIREMENTS.

***Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.***

In revising the manuscript for further consideration here, please ensure you address the specific points made by each reviewer and the editors. In your rebuttal letter you should indicate your response to the reviewers' and editors' comments and the changes you have made in the manuscript. Please submit a clean version of the paper as the main article file. A version with changes marked must also be uploaded as a marked up manuscript file.

Please also check the guidelines for revised papers at http://journals.plos.org/plosmedicine/s/revising-your-manuscript for any that apply to your paper. If you haven't already, we ask that you provide a short, non-technical Author Summary of your research to make findings accessible to a wide audience that includes both scientists and non-scientists. The Author Summary should immediately follow the Abstract in your revised manuscript. This text is subject to editorial change and should be distinct from the scientific abstract.

We expect to receive your revised manuscript within 1 week. Please email us (plosmedicine@plos.org) if you have any questions or concerns.

We ask every co-author listed on the manuscript to fill in a contributing author statement. If any of the co-authors have not filled in the statement, we will remind them to do so when the paper is revised. If all statements are not completed in a timely fashion this could hold up the re-review process. Should there be a problem getting one of your co-authors to fill in a statement we will be in contact. YOU MUST NOT ADD OR REMOVE AUTHORS UNLESS YOU HAVE ALERTED THE EDITOR HANDLING THE MANUSCRIPT TO THE CHANGE AND THEY SPECIFICALLY HAVE AGREED TO IT.

Please ensure that the paper adheres to the PLOS Data Availability Policy (see http://journals.plos.org/plosmedicine/s/data-availability), which requires that all data underlying the study's findings be provided in a repository or as Supporting Information. For data residing with a third party, authors are required to provide instructions with contact information for obtaining the data. PLOS journals do not allow statements supported by "data not shown" or "unpublished results." For such statements, authors must provide supporting data or cite public sources that include it.

If you have any questions in the meantime, please contact me or the journal staff on plosmedicine@plos.org.

We look forward to receiving the revised manuscript by Jun 05 2020 11:59PM.

Sincerely,

Thomas McBride, PhD

Senior Editor

PLOS Medicine

plosmedicine.org

------------------------------------------------------------

Requests from Editors:

1- Thank you for agreeing to make your data available in a public data repository. At this time, please provide the url of the data repository, the DOI for the dataset, and any other information needed for readers to access the dataset (including the data contact email already provided).

2- Thank you for editing your title. Is it more appropriate to include MOFICHE than PERFORM, though?

3- The url for PERFORM can be removed from the Abstract and supplied in the Introduction or Methods.

4- In the Abstract Methods and Findings section, please include the overall antibiotic prescription rate (all hospitals combined) along with the ranges. Please also specify that the ranges are across the different hospitals.

5- Thank you for providing more details in the Abstract Conclusions. This section could be a bit more succinct. For example, the second and third sentences are redundant given the previous section.

6- Please edit the last sentence of the Abstract Conclusions to read: “Until better diagnostics are available to accurately differentiate between bacterial and viral aetiologies, implementation of antimicrobial stewardship guidelines across Europe is necessary to limit antimicrobial resistance.”

7- Thank you for adding an Author Summary. The second point can be removed.

8- Additionally, please edit the “What Did the Researchers Do and Find?” section of the Author Summary could be edited for brevity, perhaps focusing on the standardized prescription rates and the prescriptions with inappropriate indication or duration.

9- Please also add “In this study we found…”, “These findings suggest...”, or similar to the “What Do These Findings Mean?” section of the Author Summary.

10- Thank you for noting ethics approval. Please provide a list (Supplemental Text is fine) of the ethics committees from the participating hospitals.

11- Please make reference to the S4 appendix (details of the regression model) in the main text Methods section.

12- S7 Appendix: typo in the title.

13- S12, S14 Appendix: Please make sure the title in the file matches the title in the list of supplemental files in the main text.

14- S15 Appendix is a file with tracked changes, please supply a clean version.

15- The data presented in Figure 2 would be better presented as a table. Please revise accordingly.

16- Please revise the stacked bar chart shown in Figure 3 as a side-by-side bar graph.

17- Figure 6: include Otitis media and Tonsillitis/pharyngitis in the title?

18- Figures 4-7: it seems there is plenty of room to provide 95% CIs in these fgures without asking the reader to open a supplementary file. Please consider adding.

19- Figures 4-8: the legends are not much use without a scale for the gradient.

20- Discussion, second paragraph: “Our study supports previous studies that reported variable antibiotic prescribing…”?

21- Discussion, final paragraph: “Until better diagnostics are available to accurately differentiate between bacterial and viral aetiologies, we strongly urge the implementation of antimicrobial stewardship guidelines to reduce antibiotic prescription in febrile children across Europe.”

22- Please move the mention of the analysis plan and the STROBE checklist to earlier in the Methods so that they appear as S1 and S2.

Comments from Reviewers:

Reviewer #1: 1) I appreciate the efforts that the authors have made to respond to the comments. I remain concerned, however, about the unclear implications of all the variation they document. The authors write in the introduction that "understanding variability is essential for the development and implementation of interventions to optimize antibiotic use." Why? They never explicitly state what the implications would be if they showed low variability versus high variability on each of their outcomes.

It appears that the five main outcomes are as follows: 1) the antibiotic prescribing rate; 2) the proportion of antibiotics that were broad-spectrum; 3) the % of antibiotics that were for appropriate (presumed bacterial), inappropriate (presumed viral) or of unclear appropriateness (viral or bacterial); 4) the % of antibiotics that were of inappropriate duration; and 5) the % of antibiotics for urinary tract infections and respiratory infections that were guideline-concordant. Here are my view of the implications of variation in each of these outcomes.

- Variability in overall antibiotic prescribing rate. Documenting variability in this rate is not that helpful in my view. The authors seem to implicitly believe that the variation implies overprescribing, but since the ideal rate of prescribing is unknown, it is unclear if the high prescribing EDs are overprescribing, if the low prescribing EDs is underprescribing, or both.

- Variability in broad-spectrum prescribing - same as above. The ideal rate of broad-spectrum prescribing is unknown.

- Variability in prescribing for antibiotic-inappropriate conditions (e.g., viruses) - documenting variability is helpful because the ideal rate of use is known (0%). If there is a lot of variation with some very high prescribing EDs, it would imply that some EDs that are doing way worse than others and therefore quality improvement initiatives should perhaps take a more targeted approach focused on the outliers. If there is little variation and the rate of prescribing among EDs is high, that would imply a more global approach is needed. If there is little variation and the rate of prescribing among EDs is consistently closer to 0%, then maybe we don't need to worry about overprescribing for viral infections.

Note that I don't feel the same about prescribing for bacterial infections - how would finding variation inform stewardship initiatives? I'm not sure it would, so it's not clear this analysis needs to be included. Also, variability in prescribing for unknown bacterial/viral infection is hard to interpret because the ideal rate of prescribing is unknown, so I'm also not sure it needs to be included.

- Variability in prescribing of inappropriate duration - this is helpful because we know the rate should be 0%

- Variability in guideline concordance - this is helpful because we know the rate should be 100%.

I would urge the authors to more explicitly walk the reader through the implications of variation in each outcome in the Discussion, using the above as points to consider incorporating. Also, in the introduction, it would be helpful to motivate the analysis by arguing that assessing the degree of variation on outcomes that should be 0% or 100% can inform whether quality improvement initiatives should be global versus targeted.

2) Presentation issues

- Abstract is hard to follow. For example, it reports guideline-concordant prescribing but does not mention earlier that this will be an outcome. It comes out of nowhere.

I would restructure as follows. State that the main outcomes are 1) the antibiotic prescribing rate; 2) the proportion of antibiotics that were broad-spectrum; 3) the % of antibiotics that were for appropriate (presumed bacterial), inappropriate (presumed viral) or of unclear appropriateness (viral or bacterial); 4) the % of antibiotics that were of inappropriate duration; and 5) the % of antibiotics for urinary tract infections and respiratory infections that were guideline-concordant. Then state that the overall rate across all children was calculated. Then state that for each outcome, variation was assessed by calculating standardized prescribing rates (i.e., the ratio between observed and expected antibiotic prescribing rate) using multilevel logistic regression models. Then in the results, report the overall result and the range in standardized prescription rates for each of the five outcomes.

- Abstract and discussion both state that antibiotic stewardship initiatives are needed until better diagnostics are available. That's simply not true. Even with perfect diagnostics, we would still need stewardship initiatives (e.g., to ensure appropriate selection and duration of antibiotics).

- In general, the manuscript is also difficult to follow. There are a lot of analyses, and they are not always "signposted" well. It would be helpful to have a section in the Methods called "Outcomes" that defines each of the five main outcomes. Then have a section called "Statistical analysis" that describes the statistics used to assess the outcomes overall and to describe variation.

- I don't think the antimicrobial resistance analysis is that helpful - it's distracting and comes out of nowhere in my view. Consider deleting.

- The prescribing for respiratory tract infections also seems a little bit extraneous, in large part because it's not clear what the ideal rate of prescribing should be for something like ear infections. Consider deleting. Readers will have an easier time digesting this very dense manuscript if there are just the five analyses for the five outcomes and if the analyses are reported in a consistent manner.

Reviewer #2: The authors have conducted a very thorough job providing additional analyses and responding to my review comments. The manuscript, upon reading, is much clearer and strengthened. I have no additional points to raise.

Any attachments provided with reviews can be seen via the following link:

[LINK]

Decision Letter 2

Thomas J McBride

28 Jul 2020

Dear Prof. Moll,

On behalf of my colleagues and the academic editor, Dr. Jean-Louis Vincent, I am delighted to inform you that your manuscript entitled "Variation in antibiotic prescription rates in febrile children presenting to Emergency Departments across Europe (MOFICHE): a multicentre observational study" (PMEDICINE-D-19-04008R2) has been accepted for publication in PLOS Medicine.

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Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Fig. Duration of prescribed antibiotics.

    (PDF)

    S2 Fig. Range of antibiotic prescriptions and broad-spectrum prescriptions by emergency department (ED) for viral, bacterial, and unknown bacterial/viral infections.

    (A) antibiotic prescriptions; (B) broad-spectrum prescriptions.

    (PDF)

    S3 Fig. Heat map of standardised broad-spectrum versus narrow-spectrum rates for viral, bacterial, or unknown bacterial/viral infections.

    (PDF)

    S1 Text. STROBE checklist.

    (PDF)

    S2 Text. Statistical analysis plan.

    (PDF)

    S3 Text. Ethics committees of participating hospitals.

    (PDF)

    S4 Text. Hospital characteristics.

    (PDF)

    S5 Text. Broad-spectrum and narrow-spectrum antibiotic definitions.

    (PDF)

    S6 Text. Local guidelines of antibiotic treatment.

    (PDF)

    S7 Text. Details of the adjusted model.

    (PDF)

    S8 Text. National and hospital antimicrobial resistance data.

    (PDF)

    S9 Text. Descriptive characteristics of cases with complete outcomes and cases with missing outcomes.

    (PDF)

    S10 Text. Variation of antibiotic and broad-spectrum prescription in lower RTIs and otitis media, tonsillitis/pharyngitis, and other upper RTIs.

    (PDF)

    S11 Text. PERFORM consortium.

    (PDF)

    Attachment

    Submitted filename: 20200228 ReplytoReviewers_final.docx

    Attachment

    Submitted filename: 20200703_Replyreviewers_rev2_final.docx

    Data Availability Statement

    An anonymized data set containing individual participant data is available in a public data repository: https://data.hpc.imperial.ac.uk/resolve/?doi=7251. DOI: 10.14469/hpc/7251. For inquiries to obtain the full dataset, please contact the data manager of the PERFORM consortium (Tisham.de08@imperial.ac.uk).


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