Pretriage criteria for identifying COVID-19-positive patients in the paediatric emergency department

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic has impacted adult and paediatric emergency departments (EDs) worldwide, necessitating structural and functional changes to maintain continuity of care.[1,2,3,4,5]

Given the known infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),[6] accurate pretriaging of potentially COVID-19-positive patients in the ED has important downstream implications to mitigate patient and staff exposure. This is especially relevant to EDs due to limitations in resources such as physical space constraints, number of negative-pressure isolation rooms and personal protective equipment (PPE) for examining potentially infected patients. Among reports of strategies implemented to modify ED processes, data on the performance of pretriage screening in effectively segregating patients are scarce.[2] We aimed to evaluate the accuracy of pretriage screening for isolating potentially COVID-positive patients in the paediatric ED.

METHODS

KK Women’s and Children’s Hospital (KKH) is an 830-bed tertiary paediatric hospital in Singapore, with an annual ED volume of approximately 150,000 patients before the COVID-19 outbreak. Our paediatric ED commenced COVID-19 polymerase chain reaction (PCR) testing from February 2020,[3] and all outpatients who fulfilled the Ministry of Health (MOH), Singapore, suspect case criteria received a PCR nasopharyngeal swab test. The eligibility criteria for PCR testing, based on MOH case definitions for suspected COVID-19 patients, incorporating travel to high-risk countries and contact history, have evolved multiple times since January 2020 as increasing information emerged locally and overseas [see Supplemental Digital Appendix].

In early February 2020, our paediatric ED initiated pretriage screening of all patients and accompanying adult caregivers (using the same criteria) at the ED entrance. This was performed by trained support staff in close consultation with clinicians, following which patients and caregivers were segregated into three risk-stratified areas where full triage assessment would take place.

Patients and caregivers considered ‘suspect’ based on quarantine status, travel history or close contact with a COVID-19 case were pretriaged to the high-risk area of the paediatric ED, an isolation facility with negative-pressure consultation rooms (including the resuscitation bay). The intermediate-risk area of the ED was used for patients with fever or acute respiratory symptoms, without the high-risk factors of quarantine, travel or significant contact with known COVID-19 cases. The low-risk area of the ED was reserved for patients with no travel or contact history, and no fever or acute respiratory symptoms.

Within these three risk-stratified areas, patients were triaged by illness severity into P1 (highest acuity), P2 or P3 (lowest acuity) cases.[4] Personal protective equipment was used in a risk-adapted manner within each ED area — surgical face masks in the low-risk area, N95 face masks and eye protection in the intermediate-risk area, and N95 face masks, eye protection, gloves and gowns in the high-risk area.[3]

We retrospectively reviewed all SARS-CoV-2 PCR nasopharyngeal swab tests of outpatients in the ED from 1 February 2020 to 31 July 2020 (the first 6 months of outpatient COVID-19 testing), with respect to patient location within the ED. COVID-19-positive status was defined as a positive PCR nasopharyngeal swab test result.[1,7] Our institution’s laboratory performed real-time reverse transcription PCR (RT-PCR) targeting the SARS-CoV-2 E gene according to the method described by Corman et al.[8] All reactions were run on a QuantStudio 5 instrument (ThermoFisher Applied Biosystems, Foster City, CA, USA). First-time positive results for individual patients were confirmed by a second assay, the RealStar SARS-CoV-2 RT-PCR kit (altona Diagnostics, Hamburg, Germany) on a CFX96 thermocycler (Bio-Rad, Hercules, CA, USA).

ED pretriage screening was evaluated using descriptive analyses to compare COVID-19 results (positive vs. negative) with the ED location to which patients were pretriaged (high-risk vs. low-/intermediate-risk areas). Information on COVID-19 test results and ED patient location (a key data field that is accurately entered by clinical staff for each patient’s real-time management) was obtained from the hospital electronic medical records. Ethics approval was granted by the hospital Institutional Review Board (reference 2020/2760).

RESULTS

A total of 42,511 children attended the ED during the study period; 2,908, 22,459 and 17,144 children were pretriaged to the high-risk area, intermediate-risk area and low-risk area, respectively. Apart from the 606 (20.8%) children seen in the high-risk area who were asymptomatic close contacts of confirmed cases, all other children were symptomatic. A total of 5,625 COVID-19 outpatient nasopharyngeal swab tests were done in the ED. The proportion of patients receiving a COVID-19 swab test in each area was 1,773/2,908 (61.0%) in the high-risk area and 3,852/22,459 (17.1%) in the intermediate-risk area. In the high-risk area, 66 out of 1,773 (3.7%) COVID-19 swab tests were positive, while in the intermediate-risk area, one out of 3,852 (0.025%) COVID-19 swab tests was positive. The overall prevalence of COVID-19-positive patients among those who received a swab test was 1.2% (67/5,625). Only one patient from the intermediate-risk area tested positive for COVID-19 — a 7-year-old boy with bronchopneumonia, who had prolonged cough and no travel or contact history.

DISCUSSION

In our paediatric ED setting, pretriage screening was effective in separating COVID-19-positive and -negative patients, with only one (0.025%) patient in the intermediate-risk areas subsequently testing positive. The single positive case in the intermediate-risk category was eligible for testing due to symptoms and signs of community-acquired pneumonia, even in the absence of contact or travel history, suggesting the existence of some degree of community spread of COVID-19 at that point of the outbreak. He was unlikely to have been a false positive, given that all positive results for individual patients were confirmed by a second assay using a different COVID-19 RT-PCR test.

Table 1 compares the criteria for pretriage, COVID-19 testing eligibility, COVID-19-positive status and results of pretriage screening from our paediatric ED in Singapore, compared to the published data from adult EDs in Singapore and Italy, respectively.[1,2] The following may explain different results of pretriage screening in Singapore paediatric and adult EDs. Firstly, opposite COVID-19 testing eligibility criteria were used: the paediatric ED cohort who was tested consisted of outpatients before ED discharge, while the adult ED cohort consisted of inpatients admitted via the ED. Secondly, the broader internal screening criteria used in the adult ED included anosmia, which is more readily elicited in adults than children. On the other hand, Merano General Hospital in Italy reported a high proportion of COVID-19-positive patients among those tested in the infected area using their adult ED pretriage criteria, possibly because it was the designated hospital in South Tyrol for treatment of COVID-19 patients.[2]

Table 1.

Comparison of ED criteria across hospitals^a.

Criterion	KK Women’s and Children’s Hospital	Singapore General Hospital		Merano General Hospital
		Official case criteria	Internal screening criteria
Pretriage criteria	High risk: Patients or caregivers considered ‘suspect’ based on quarantine status, travel history or contact with COVID-19 caseb Intermediate risk: Fever or acute respiratory symptoms Low risk: No travel or contact history, no fever or acute respiratory symptoms	Isolation as suspect COVID-19 case: Pneumonia or severe respiratory infection with breathlessness plus travel history, close contact with COVID-19 case, occupation/living environment with high risk of COVID-19 exposure	Isolation as suspect COVID-19 case: As per official MOH criteria, plus anosmia, earlier addition of affected countries and subsequent expansion of travel history to all countries	Infected area: Fever ≥37.5°C, flulike symptoms or dyspnoea (hypoxia with oxygen saturation <95% or tachypnoea with respiratory rate >20) Clean area: No to all of the above
Eligibility for COVID-19 testing	Outpatients who fulfilled Singapore MOH suspect case criteriab	All patients admitted via the ED and presenting with respiratory symptoms at ED triage	Not available	Eligibility for COVID-19 testing
Criteria for COVID-19 positive status	Positive PCR nasopharyngeal swab test	Positive RTPCR test of respiratory sample	Positive nose–throat swab within 15 days of an ED visit or chest CT suggestive of interstitial pneumonia	Criteria for COVID-19-positive status
Proportion of COVID-19 positive cases (of those tested)	High-risk area: 3.7% Intermediate-risk area: 0.025%	Isolation area: 15.6%c Non-isolation area: 2.2%c	Isolation area: 8.5%c Non-isolation area: 0.9%c	Infected area: 50.5%c Clean area: 0.5%c
Prevalence of COVID-19 positive cases (of those tested)	1.2%	3.8%c	–	5.0%c

^aKK Women’s and Children’s Hospital, Singapore: paediatric ED (current study), 1 Feb 2020 to 31 Jul 2020; Singapore General Hospital, Singapore: adult ED, 1 Jan 2020 to 1 Apr 2020; Merano General Hospital, Italy: adult ED, 4 Mar 2020 to 31 Mar 2020. ^bDetails are found in the Supplemental Digital Appendix. ^cCalculated based on data provided in studies.[1,2] COVID-19: coronavirus disease 2019, CT: computed tomography, ED: emergency department, MOH: Ministry of Health, PCR: polymerase chain reaction, RTPCR: reverse transcription polymerase chain reaction

Our study had some limitations. First, as our study population included all children attending the ED (including those with presenting complaints unrelated to COVID-19), and the reference standard (PCR test) was not done for all patients, our study should not strictly be considered a diagnostic accuracy study. Second, the prevailing hospital policy was to swab only outpatients before ED discharge, while patients requiring admission received their swab as inpatients. The swab results thus pragmatically reflected those of outpatients. Third, the fluidity of the COVID-19 outbreak situation during the initial few months meant that MOH case definitions evolved continuously over the study time frame, with multi-agency monitoring and feedback. Fourth, each ED utilised slightly different pretriage criteria, ranging from primarily clinical parameters[2] to a composite of clinical and anamnestic data (such as travel and contact history).[1] The relative merits of each pretriage strategy may ultimately be decided based on what is practical in each ED’s particular circumstances, coupled with best available evidence. Nonetheless, given the scarcity of available data, it is instructive to gauge the performance of ED pretriage screening across a spectrum of settings.

The principles of pretriage screening remain relevant even if the criteria are fluid as the disease itself evolves. Taken together, our paediatric ED experience and that of adult EDs[1,2] show that pretriage has the potential to prevent nosocomial spread of COVID-19, balancing patients’ medical needs with ED resource optimisation during this unprecedented infectious disease pandemic.

Conflicts of interest

There are no conflicts of interest.

Supplemental digital content

Appendix at http://links.lww.com/SGMJ/A290

APPENDIX.

COVID-19 Case Definitions by the Ministry of Health, Singapore over the course of the COVID-19 outbreak

Date	Case Definition
2 January 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND travel to or residence in Wuhan city within the last 14 days; or b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness, had close contact with a pneumonia case of unknown cause linked to the Wuhan cluster.
21 January 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND travel to mainland China within the last 14 days; or b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness, had been to a hospital in mainland China or had close contact with a case of 2019 novel coronavirus infection.
23 January 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND travel to mainland China within 14 days before onset of illness; or b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness, had been to a hospital in mainland China or had close contact with a case of 2019 novel coronavirus infection.
25 January 2020	a)A person with respiratory infection with breathlessness AND travel to mainland China within 14 days before onset of illness; or b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness who had:  i.Been to Wuhan city or Hubei Province, China; OR  ii.Been to a hospital in mainland China; OR  iii.Had close contact with a case of 2019 novel coronavirus infection.
4 February 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND travel to mainland China within 14 days before onset of illness; or b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness had:  i.Been to Hubei Province (including Wuhan city) or Zhejiang Province (including Hangzhou city), China; OR  ii.Been to a hospital in mainland China; OR  iii.Had close contact with a case of 2019 novel coronavirus infection; OR  iv.Had frequent or close contact during work with recent travellers from mainland China (travel history in the last 14 days).
23 February 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND travel to:  i.mainland China; OR  ii.Daegu City or Cheongdo County, South Korea. b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness had:  i.Been to Hubei Province (including Wuhan city) or Zhejiang Province (including Hangzhou city), China; OR  ii.Been to a hospital in mainland China; OR  iii.Had close contact with a case of COVID-19 infection.
3 March 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND who within 14 days before onset of illness had travelled to affected areas as listed on the Healthcare Professionals Portal (Mainland China, Republic of Korea, Japan, Northern Italy (including Milan and Venice) and Iran). b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness had:  i.Been to Hubei Province (including Wuhan city), China, Daegu city or Cheongdo County, Republic of Korea; OR  ii.Been to a hospital in affected areas; OR  iii.Had close contact with a case of COVID-19 infection.
10 March 2020	a)A person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness AND who within 14 days before onset of illness had travelled abroad (i.e. to any country outside of Singapore). b)A person with an acute respiratory illness of any degree of severity who, within 14 days before onset of illness had:  i.Been to any of the areas requiring heightened vigilance1 as listed on the Healthcare Professionals Portal: https://www.moh.gov.sg/hpp/all-healthcare-professionals; OR  ii.Been to any hospital abroad; OR  iii.Close contact with a case of COVID-19 infection. 1Refers to affected areas with high disease load or high connectivity to Singapore. As of 9 March 2020, these are: Mainland China, Republic of Korea, Italy, Iran, France, Germany, Spain, Japan and the United Kingdom.
8 May 2020	a) A person with clinical signs and symptoms suggestive of Community- Acquired Pneumonia1
	b)A person with an acute respiratory illness of any degree of severity (e.g. symptoms of cough, sore throat, runny nose, anosmia), with or without fever, who, within 14 days before onset of illness had:  i.Travelled abroad (outside Singapore); OR  ii.Close contact2 with a case of COVID-19 infection; OR  iii.Stayed in a foreign worker dormitory3; OR  iv.Worked in occupations or environments with higher risk of exposure to COVID-19 cases4 c)Any person with prolonged febrile5 acute respiratory infection (ARI) symptoms of 4 days or more, and not recovering 1Excludes cases of nosocomial pneumonia and aspiration pneumonia with no links to confirmed cases. 2Close contact is defined as:  • Anyone who provided care for the patient, including a health care worker or family member, or who had other similarly close physical contact;  • Anyone who stayed (e.g. household members) at the same place as a case; or  • Anyone who had close (i.e. less than 2m) and prolonged contact (30 min or more) with a case (e.g. shared a meal). 3Separate processes apply to foreign workers from a dormitory that has dedicated medical station/clinic or dedicated workflow for assessment and swabbing. 4These include but are not limited to any staff (healthcare worker and non- healthcare worker) working in:  • Public and private healthcare settings, spanning acute care, primary care, intermediate and long-term care and community care settings  • Dormitories or involved in dormitory outbreak control operations  • Isolation / quarantine facilities  • Community care facilities (CCFs)/ community recovery facilities (CRFs)  • Ambulance and dedicated patient transport (including private hire vehicles). 5Fever, of any duration, with measured or reported temperature of > 37.5°C.

Funding Statement

Nil.