Leung 2021.

Study characteristics
Patient Sampling	Purpose: diagnosis of SARS‐CoV‐2 infection (mild COVID‐19 disease); to review the characteristics and outcomes of individuals who attended a testing centre Design: cross‐sectional cohort study, retrospective data collection Recruitment: all patients attending the testing centre (temporary outpatient testing centre at the AsiaWorldExpo) Sample size: n = 1258 (86 cases) Inclusion criteria: all patients presenting to the testing centre Exclusion criteria: missing data and immediate referral to regional ED
Patient characteristics and setting	Definition cases: positive RT‐PCR test for SARS‐CoV‐2 Definition controls: negative RT‐PCR test for SARS‐CoV‐2 Country: Hong Kong (China) Dates: 20 March 2020‐19 April 2020 Symptoms and severity: 96% of all participants symptomatic, mostly mild severity, acutely ill patients were immediately referred to ED Demographics: age: controls mean 27.1 years, cases mean 30.6 years M%/F%: cases 53.5/46.5, controls 51.7/48.3 Non‐Chinese ethnicity overall 10% Exposure history: not specified
Index tests	Fever Documented fever Reported fever Chills Cough Runny nose Sore throat Vomiting Diarrhoea Fatigue Myalgia Headache Anosmia
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: RT‐PCR, pooled nasopharyngeal and throat swabs
Flow and timing	Timing not specified, but both index tests and RS taken at outpatient test centre, so all tests and assessments should have been done at the time of presentation
Comparative
Notes	Funding: none declared
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	Yes
Could the selection of patients have introduced bias?		Low risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Unclear
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	No
Could the patient flow have introduced bias?		Low risk