Hüfner 2020.

Study characteristics
Patient Sampling	Purpose: diagnosis of SARS‐CoV‐2 infection (mild COVID‐19 disease) ‐ to identify patients in the ED early using a score so that they can be isolated pre‐emptively Design: cross‐sectional cohort study, retrospective data collection Recruitment: all patients who presented at 1 of 3 ED's Sample size: n = 697 (64 cases) Inclusion criteria: all patients presenting at one of the participating EDs and scoring at least 1 item of the COVID score Exclusion criteria: none specified
Patient characteristics and setting	Facility cases: positive RT‐PCR for SARS‐CoV‐2 Facility controls: negative RT‐PCR for SARS‐CoV‐2 Country: Germany Dates: 9 March 2020‐30 April 2020 Symptoms and severity: all symptomatic patients, 79.7% of cases hospitalised, 53.1% of controls Demographics: age: controls mean 54.7 years, cases mean 60.3 years M%/F%: cases 68.8/31.2, controls 46.9/53.1 Exposure history: not specified
Index tests	Fever > 37.3 ° C and/or chills (Irritant) cough with/without sputum Impairment of the sense of smell or taste Sore throat Fatigue (malaise, tiredness) Headache Body aches (muscles, joints) Runny nose GI symptoms (unspecific abdominal complaints, diarrhoea, vomiting)
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: RT‐PCR for SARS‐CoV‐2 (nasopharyngeal and oropharyngeal swab) or chest X‐ray or CT
Flow and timing	Timing not specified
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?		Unclear 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?	Unclear
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?			Unclear
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?	No
Were all patients included in the analysis?	Unclear
Could the patient flow have introduced bias?		Unclear risk