Ahmed 2021.

Study characteristics
Patient Sampling	Purpose: diagnosis of SARS‐CoV‐2 infection (mild COVID‐19 disease); to compare demographic characteristics of patients who received positive and negative test results for SARS‐CoV‐ 2 in a population with higher testing rates than among previously published cohorts Design: multicenter cross‐sectional cohort study, retrospective data collection Recruitment: all patients tested for SARS­CoV‐2 in the UHealth system during the study period were eligible for this cohort study. For a random subset of patients tested during 10‐31 March 2020, symptom data were manually extracted from medical records from 24 h before and 24 h after SARS‐CoV‐2 testing. Medical records were selected to include at least 20% of patients tested on each day, for a total of 1821 patients. Sample size: n = 1821 (123 cases) 2021 Inclusion criteria: all patients tested for SARS‐CoV‐2 in the UHealth system during the study period. Test eligibility required at least 1 of the following symptoms ‐ cough, fever, shortness of breath, or a high risk of exposure given recent travel or contact with a person who tested positive. Exclusion criteria: none specified
Patient characteristics and setting	Facility cases: positive SARS‐CoV‐2 test. Primarily outpatient settings Facility controls: negative SARS‐CoV‐2 test. Primarily outpatient settings Country: Utah, USA Dates: 10 March 2020‐31 March 2020 Symptoms and severity: not specified. Primarily mild to moderate severity Demographics: median age cases: 38.2 years controls: 39.6 years. Gender: % female cases: 45.8%, controls: 56.7% (entire cohort) Exposure history: previous exposure: 56% of cases, 28% of controls; travel: 45% of cases, 25% of controls
Index tests	Cough Fever Shortness of breath Lethargy Myalgia Headache Sore throat Nasal symptoms Diarrhoea Nausea/vomiting
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: RT‐PCR for SARS‐CoV‐2 (specimen not specified)
Flow and timing	Time interval not specified
Comparative
Notes	Funding: supported by the National Institute of Allergy and Infectious Diseases (R01 AI135114 to D.T.L.) and the National Heart, Lung, and Blood Institute (K08 HL13650 to R.U.S.) of the National Institutes of Health; and the Centers for Disease Control and Prevention (5U01CK000555‐02 to M.H.S. and 5U01CK000538‐03 to M.H.S. and L.T.K.)
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?	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?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear 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?	Unclear
Were all patients included in the analysis?	No
Could the patient flow have introduced bias?		Unclear risk