Kelen 2021.

Study characteristics
Patient Sampling	Purpose: diagnosis of SARS‐CoV‐2 infection (mild COVID‐19 disease); to understand the impact of COVID‐19 on EDs Design: cross‐sectional cohort study, retrospective data collection Recruitment: consecutive: all patients of at least 15 years of age presenting at ED with symptoms suggestive of COVID‐19 or with high acuity Sample size: n = 11402 (2484 cases) Inclusion criteria: at least 15 years old and symptoms suggestive of COVID‐19 symptoms or high acuity Exclusion criteria: none specified
Patient characteristics and setting	Facility cases: positive RT‐PCR test for SARS‐CoV‐2 Facility controls: negative RT‐PCR test for SARS‐CoV‐2 Country: USA Dates: 16 March 2020‐15 May 2020 Symptoms and severity: mild to moderate severity; acuity triage score 1 (highest) 4.7%; 2 22.9%; 3 55.3%; 4 14.1%; 5 1.6%; not listed 1.3% Demographics: age overall: 15‐24 years: 31.8%, 25‐34 years: 33.7%, 35‐44 years: 39.3%, 45‐54 years: 42.1%, 55‐64 years: 45.2%, 65‐74 years: 48.1%, 75+ years: 52.6% M%/F%:overall (all those tested) 40.7/59.3 Exposure history: not specified
Index tests	Fever Constitutional symptom Pulmonary Hypotension Shortness of breath Altered mental status Weakness Syncope Headache Nausea/vomiting/diarrhoea Obstetric/gynaecological symptoms (pregnancy related)
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: RT‐PCR, nasopharyngeal swabs
Flow and timing	Index test and RS both taken upon arrival at ED
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?	Unclear
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?	No
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?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Low risk