Cost of pediatric pneumonia episodes with or without chest radiography

Abstract

Background and Objective:

Despite its routine use, it is unclear whether chest radiograph (CXR) is a cost-effective strategy in the work-up of community-acquired pneumonia (CAP) in pediatric emergency department (ED).We sought to assess the costs of CAP episodes with and without CXR among children discharged from the ED.

Methods:

This was a retrospective cohort study within the Healthcare Cost and Utilization Project State ED and Inpatient Databases of children 3 months to 18 years with CAP discharged from any EDs in 8 states over 5 years. We evaluated total 28-day costs following ED discharge, including the index visit and subsequent care. Mixed-effects linear regression models adjusted for patient-level variables and illness severity were performed to evaluate the association between CXR and costs.

Results:

We evaluated 225,781 children with CAP, and 86.2% had CXR at the index ED visit. Median costs of the 28-day episodes, index ED visits, and subsequent visits were $314 (interquartile range (IQR) 208-497), $288 (IQR 195-433), and $255 (IQR 133-637), respectively. There was a $33 (95% CI 22-44) savings over 28-days per patient for those who received a CXR compared to no CXR after adjusting for patient-level variables and illness severity. Costs during subsequent visits ($26 savings, 95%CI 16, 36) accounted for the majority of the savings as compared to the index ED visit ($6, 95%CI 3, 10).

Conclusions:

Performance of CXR for CAP diagnosis may be a cost-effective strategy when considering the downstream provision of care among patients who require subsequent healthcare after initial ED discharge.

Introduction

Diagnostic evaluation for pediatric community-acquired pneumonia (CAP) in the emergency department (ED) is both common and costly.^1-4 The role of chest radiograph (CXR) in CAP diagnosis is a frequent topic of debate and investigation in the literature.^5-13 The Infectious Diseases Society of America recommends against the routine use of CXR for CAP diagnosis among children who do not require hospitalization and instead recommends diagnosis based on clinical exam.¹⁴ However, clinicians frequently perform CXR for CAP diagnosis given the limitations in the history and clinical exam at identifying CAP and complicated CAP .^12,14 Understanding the costs of CXR for individuals and society are integral in defining its diagnostic utility, particularly given its known limitations as a diagnostic tool.¹⁴

Further characterizing the costs of CXR and the potential to avert future healthcare utilization and associated CAP complications could inform national guidelines for CAP diagnosis and bring standardization to a disease which is associated with significant diagnostic variation.^15,16 Cost-effectiveness analyses have been performed to evaluate the impact of CXR in other common pediatric respiratory illnesses such as bronchiolitis.¹⁷ Prior studies have evaluated the impact of patient-level factors and institutional clinical pathways on CAP costs.^18,19 One single-center study found that CXR was more expensive than point-of-care lung ultrasound in pediatric CAP diagnosis at the time of the index ED visit.²⁰ However, the cost-effectiveness of CXR compared to clinical diagnosis for overall pediatric CAP costs is unclear.

The aim of this study was to assess the costs of 28-day CAP episodes with and without CXR among children discharged from the ED with CAP. We hypothesized that performing a CXR at time of initial diagnosis would be associated with lower overall 28-day costs with the rationales that (1) CXR may allow for more timely diagnosis of complicated pneumonia requiring admission and early intervention and (2) decrease return visits for further diagnostic clarity.

Methods

Study Design

This was a retrospective cohort study of children discharged with a diagnosis of CAP from any ED within the Healthcare Cost and Utilization Project State ED and Inpatient Databases of Arkansas, Florida, Georgia, Iowa, Maryland, Nebraska, New York, and Wisconsin. The databases contain administrative data on all ED and inpatient encounters in each state. These specific states were chosen for their data quality and together included 20.9% of the national child population in 2019.

Inclusion Criteria

We included children 3 months to 18 years discharged with a diagnosis of CAP between July 1, 2014 and September 30, 2019 using a previously-validated International Classification of Diseases, Ninth Revision Clinical Modification (ICD-9) code set (test characteristics according to reference standard of provider-confirmed CAP: sensitivity of 64%, specificity of 96%, positive predictive value 89%, negative predictive value 84%) and the corresponding International Classification of Diseases, Tenth Revision Clinical Modification (ICD-10) codes (Supplemental Table 1).^12,21

Exclusion Criteria

We excluded EDs with poor data quality where there was potential for incomplete or inaccurate data coding. Poor data quality was defined by identifying the proportion of patients who were diagnosed with an extremity fracture and did not have an associated code for radiographic imaging.²² EDs where <70% of children with an extremity fracture were discharged without a code for radiographic imaging were excluded from analysis. This was based on the authors’ clinical experience in both pediatric and community hospitals, in which patients with an extremity fracture diagnosis nearly always undergo radiography.

We excluded patients without a unique longitudinal patient identifier or those who were transferred without a record from the receiving hospital. Children with complex chronic conditions, co-diagnosis of aspiration pneumonia or complicated CAP, any-cause hospitalization within the previous 30 days, or prior ED visit or hospitalization for CAP within 6 months were excluded.^1,23,24 Children who left against medical advice or were discharged to a home healthcare facility were also excluded.

Exposure and Outcomes

CXR was the primary exposure and was identified using procedure codes (Supplemental Table 1). We evaluated total costs within the 28-day period following ED discharge for CAP, inclusive of the index visit and all subsequent ED and hospital care. Costs were calculated using ED-level charges and multiplied by cost-to-charge ratios specific to each ED for each year. Charges in the database reflect the amount billed by for hospital services, but not specific costs. The cost-to-charge ratios were developed as part of the database to estimate the actual cost of services.

Variables

Patient-level variables included in analysis included age (categorized based on prior literature into 3-11 months, 1-5 years, 6-10 years, and 11-18 years), sex, primary payer, weekend versus weekday presentation, and asthma co-diagnosis (defined by ICD-9 and ICD-10 codes).^14,25,26

To adjust for underlying CAP severity, we identified whether parenteral antibiotics or laboratory testing (i.e., complete blood count, blood culture, inflammatory markers, nasopharyngeal and blood viral studies) were performed in the ED using procedure codes (Supplemental Table 1).

Analysis

Descriptive statistics, including median and interquartile range (IQR), were used to report the costs of the index ED visit, subsequent visits, and full 28-day CAP episodes, stratified by performance of CXR at the index ED visit. Costs were winsorized at the 0.5th and 99.5th percentiles. Differences in baseline patient characteristics among those with and without CXR at the index visit were evaluated using chi-square tests.

To adjust for patient-level confounders and markers of illness severity (performance of laboratory testing and/or administration of parenteral antibiotics), we constructed a mixed-effects linear regression model with costs as the outcome variable, CXR as the exposure, and all patient-level variables. In a post-hoc exploratory analysis, we repeated the regression model restricting only to those who did not require a subsequent admission after initial discharge from the index ED visit. This exploratory analysis was performed to determine whether the association between CXR and 28-day costs was preserved among the majority of patients who did not require subsequent admission.

We performed Wilcoxon rank sum tests to compare costs among those who did and did not receive antibiotics or labs at the index ED visit. Finally, we plotted cumulative mean costs for each day using the index visit arrival as day 0. We stratified the plot by CXR and laboratory testing, since laboratory tests generate costs and are also associated with the likelihood of CXR . We performed Wilcoxon rank sum tests evaluating overall 28-day costs among those with and without CXR who received laboratory testing at the index ED visit and among those with and without CXR who did not receive laboratory testing at the index ED visit.

Results

We evaluated 225,781 (64.2%) of the 351,884 children who were discharged from the ED with a diagnosis of CAP (Figure 1). Most (86.2%) children in the cohort had CXR at their index ED visit (Table 1). The majority of children in the cohort were between 1-5 years of age, had public insurance and were evaluated in an urban ED. Children who had a CXR at initial evaluation were more likely to receive intravenous antibiotics (20.2% vs. 11.9%, p<0.001) and have laboratory testing (47.1% vs. 15.6%, p<0.001).

Figure 1.

Patient flow diagram.

Table 1:

Baseline Characteristics of Patients with and without CXR at the Index Visit

Characteristic	No CXR at Index Visit N(%) n=31,269 (13.8%)	CXR at Index Visit(%) n=194,512 (86.2%)	P-value
Age (years)			<0.001
<1	2,832 (9.1)	23,865 (12.3)
1-5	17,278 (55.3)	108,564 (55.8)
6-10	6,839 (21.9)	37,413 (19.2)
11+	4,320 (13.8)	24,670 (12.7)
Male	16,526 (52.9)	104,406 (53.7)	<0.001
Payer			<0.001
Government	19,714 (63.0)	129,400 (66.5)
Private	8,549 (27.4)	47,317 (24.3)
Uninsured	2,010 (6.4)	11,352 (5.8)
Other	926 (2.9)	6,264 (3.2)
Weekend Presentation	9,472 (30.3)	60,699 (31.2)	<0.001
Asthma History	3,585 (11.5)	26,091 (13.4)	<0.001
Intravenous 3rd Generation Cephalosporin	3,200 (10.2)	37,233 (19.1)	<0.001
Other Intravenous Antibiotic	684 (2.2)	3,353 (1.7)	<0.001
Parenteral Antibiotics	3,710 (11.9)	39,213 (20.2)	<0.001
Laboratory Testing	4,892 (15.6)	91,557 (47.1)	<0.001
ED State			<0.001
Arkansas	3,539 (11.3)	3,187 (1.6)
Florida	2,995 (9.6)	41,976 (21.6)
Georgia	10,759 (34.4)	40,683 (20.9)
Iowa	1,216 (3.9)	11,444 (5.9)
Maryland	2,158 (6.9)	22,515 (11.6)
Nebraska	618 (2.0)	5,214 (2.7)
New York	7,567 (24.2)	50,039 (25.7)
Wisconsin	2,417 (7.7)	19,454 (10.0)
Rural ED Location	4,689 (15.0)	31,524 (16.2)	<0.001

Median costs of the 28-day episodes, index ED visits, and subsequent visits were $314 (interquartile range (IQR) 208-497), $288 (IQR 195-433), and $255 (IQR 133-637), respectively (Table 2). Median unadjusted total 28-day costs were $324 (IQR 218-505) and $244 ($146-432) among patients with and without CXR, respectively. However, after adjusting for patient-level variables and illness severity, CXR at the index ED visit was associated with a $33 (95% CI 22-44) 28-day savings per patient who received a CXR. The total predicted cost savings if CXR had been performed in all patients in the cohort was $1,023,122 (95%CI 684,166-1,362,078). Of the 5,683 (2.5%) children who required admission after discharge from the index ED visit, the median cost of subsequent visits was $3,832 (IQR 2,396-6,636) among children with CXR and $3,862 (IQR 2,317-7,067) among children without CXR. Median cost of subsequent visits among the 1,002 (0.4%) children who required ICU admission was $8,226 (IQR 5,527-8,226) among children with CXR and $8,226 (IQR 5,742-8,226) among children without CXR. Among the 220,067 patients (97.5%) of patients who did not require a subsequent admission, median costs of the 28-day episodes were $308 (IQR 205-476), and CXR at the index ED visit was associated with an increased 28-day cost after adjusting for patient-level variables and illness severity (increase of $3, 95%CI 0, 5).

Table 2:

Association between CXR Utilization during an ED Discharge for Pneumonia and 28-days costs of the Pneumonia Episode

Cost	All patients Median (IQR)	CXR Median (IQR)	No CXR Median (IQR)	Unadjusted ß (95% CI)	Adjusted ß (95% CI)
Total 28-day	314.41 (207.64-496.97)	323.82 (218.22-504.81)	243.96 (146.16-431.56)	57.53 (46.71, 68.36)	−32.72 (−43.56, −21.88)
Index ED visit	287.70 (195.27-432.95)	297.01 (205.97-441.12)	217.34 (139.12-361.60)	60.83 (56.83, 64.83)	−6.38 (−10.03, −2.73)
Subsequent visits †	255.01 (132.80-636.65)	254.22 (132.45-620.29)	261.04 (134.79-727.34)	−3.30 (−13.05, 6.46)	−26.34 (−36.35, −16.33)
Admission	3,835.70 (2,390.80-6,678.19)	3,831.88 (2,395.63-6,636.66)	3,861.51 (2,317.05-7,067.36)	−85.63 (−268.34, 97.58)	−73.87 (−264.68, 116.93)
ICU Admission	8,225.70 (5,543.64-8,225.70)	8,225.70 (5,526.58-8,225.70)	8,225.70 (5,741.69-8,225.70)	0.88 (−347.80, 349.56)	246.35 (−116.44, 609.14)

^*Adjusted ß, adjusted for age, sex, payer, weekend/weekday visit, asthma, parenteral antibiotic administration, and any labs performed.

^†Subsequent visits include all revisits and hospitalizations initiated within 28-days of discharge from the index ED visit.

In the overall cohort, 42.7% of children received laboratory testing and 19.0% received parenteral antibiotics at the index ED visit. Median unadjusted index costs among those who did and did not have laboratory testing were $385 (IQR 260-587) and $239 (IQR 166-338, p<0.001) and among those who did and did not receive parenteral antibiotics were $430 (IQR 276-984) vs. $266 (IQR 184-389, p<0.001).

Among children without laboratory testing at the index ED visit, children who had a CXR at time of initial diagnosis had lower mean cumulative 28-days costs as compared to children who did not have a CXR at time of initial diagnosis (Figure 2, mean (standard deviation, sd) $400 (712) vs. $402 (833), p<0.001). Similarly, among children who did have laboratory testing at the index ED visit, performance of a CXR was associated with overall 28-day cost savings (mean (sd) $694 (1053) vs. $908 (1290), p<0.001).

Figure 2.

Mean cumulative 28-days CAP costs stratified by performance of CXR and laboratory testing at the index ED visit. Mean cumulative 28-day CAP costs among children with laboratory alone (dark red), cxr and laboratory (light red), no CXR or laboratory testing (dark blue), and CXR alone (light blue).

Discussion

This study aimed to determine the potential impact of clinical versus radiographic CAP diagnosis on costs of CAP-associated care. Understanding this association is important given the challenges associated with CAP diagnosis. Not only is the CAP clinical exam unreliable, but there is also conflicting evidence supporting the use of CXR for CAP diagnosis and guidelines which specifically recommend against its routine use.^14,27 We have evaluated this association across both tertiary care and low-pediatric volume EDs, thus making our findings widely generalizable. We found that performance of CXR at the time of CAP diagnosis in the ED is associated with a small, but significant 28-day cost-savings, particularly among patients who require subsequent care. This finding suggests that CXR may be a cost-effective strategy among children who require subsequent healthcare after initial discharge from the ED.

CXR was associated with a 28-day cost savings across patients who did or did not receive laboratory testing. However, the savings was larger among children who required laboratory testing than those who did not. These findings suggest that CXR may be most beneficial among children with higher illness severity who are more likely to require subsequent visits for CAP-related care. Given the lack of clinical data in the database, we are limited in our ability to determine why CXR is cost-saving. We hypothesize that clinicians may be using CXR in their clinical decision-making regarding disposition from the ED visit, identifying children with CAP who are at lower risk for revisit. Alternatively, CXR may provide a more reliable CAP diagnosis than the clinical exam. Children with clinically diagnosed CAP may have other non-CAP diagnoses which require return to care for definitive treatment.

Most children in the cohort did not require subsequent visits after initial discharge from their index ED visit. In the children who did not require subsequent care, CXR was not a cost-saving strategy and instead was associated with slightly increased 28-day costs, likely reflective of the index costs associated with actual CXR performance. This finding suggests that the cost savings of CXR are due entirely to the prevention of downstream care.

While our findings demonstrate that CXR performance offers a small, but significant 28-day cost savings, the modest cost savings observed in this study preclude a blanket recommendation for or against the routine use of CXR in the diagnosis of CAP, based on cost alone. However, our findings clearly demonstrate that CXR diagnosis is at least non-inferior to clinical diagnosis from a cost perspective among children with CAP who do and do not require downstream care after ED discharge. Prior studies have shown that CXR performance offers improved diagnostic accuracy over the clinical exam and likely allows for earlier detection of complicated pneumonias.²⁷ When considering these benefits and our findings that CXRs do not add to overall costs of care, CXR performance, on balance, may be worthwhile. Still, CXR may be most beneficial among children at higher risk for severe CAP and who may require subsequent care. While studies are ongoing to develop prediction models, there is currently no standardized approach to accurately identify children at risk of severe CAP.^28-30 With the development of these models, clinicians may ultimately be able to use CXR at time of diagnosis as a cost effective strategy that may minimize the need for downstream provision of care.

There are several important limitations to this study. The claims dataset utilized in this study did not include clinical data. Thus, we were limited in our ability to assess underlying patient illness severity which likely impacted decision-making around CXR performance and overall 28-day costs. However, we were able to ascertain performance of laboratory testing and administration of parenteral antibiotics which we incorporated as markers of illness severity in our primary analysis. Ambulatory centers were not captured in this database, and thus we were unable to ascertain costs of CAP episodes in this setting. Importantly, this study was not able to address costs associated with CXR among those children who received CXR for suspicion for CAP but were ultimately discharged from the ED without a diagnosis of CAP. The costs of CXR in these patients are important when considering the overall costs of CXR among children who are undergoing CAP work-up. In addition, we were unable to identify costs associated with provision of care outside of the primary database. However, the database in this study incorporates all ED and inpatient encounters within a given state. Approximately one-quarter of the cohort was excluded given lack of a longitudinal patient identifier which may have contributed to underlying selection bias. Additionally, this study did not address costs associated with CXR among those children who received CXR for suspicion for CAP but were ultimately discharged from the ED without a diagnosis of CAP.

In this large retrospective cohort study of tertiary and community EDs, we found that CXR was associated with a 28-day cost savings among children discharged from the ED with a diagnosis of CAP. Subsequent costs among the minority of children who required subsequent admission after initial ED discharge accounted for the majority of the observed cost savings. Therefore, CXR may be a cost-effective strategy among children with CAP by averting subsequent healthcare after initial discharge from the ED. Future studies, incorporating decision analysis or a prospective cohort, are needed to determine whether the observed cost benefit among children with CAP outweigh the costs of negative CXRs performed among children undergoing CAP work-up who receive an alternative diagnosis.

Abbreviations:

CXR

chest radiograph

CAP

community-acquired pneumonia

ED

emergency department

ICD-9

International Classification of Diseases, Ninth Revision Clinical Modification

ICD-10

International Classification of Diseases, 10th Revision Clinical Modification

ICU

intensive care unit