Alizadehsani 2021.

Study characteristics
Patient Sampling	Purpose: diagnosis of COVID‐19 pneumonia; to identify risk factors for disease and mortality Design: cross‐sectional cohort, prospective data collection Recruitment: all patients referred to the imaging department through the ED on suspicion of COVID‐19 (with flu‐like symptoms) Sample size: n = 319 (123 cases) Inclusion criteria: patients with flu‐like symptoms referred to the imaging department Exclusion criteria: none specified
Patient characteristics and setting	Facility cases: patients with positive findings on lung CT Facility controls: patients with negative lung CT Country: Iran Dates: 01 March 2020‐08 April 2020 Symptoms and severity: not specified. 1/3 had COVID‐19 pneumonia Demographics: mean age cases: 52.0 years controls: 44.1 years M%/F%: cases 40.8/59.2, controls 50.4/49.6 Exposure history: travelling in past 3 months: cases 4.9%, controls 3.1%
Index tests	Fever Dyspnoea Weakness Shivering Fatigue Dry cough Anorexia Anosmia Ageusia Dizziness Sweating
Target condition and reference standard(s)	TC: COVID‐19 pneumonia RS: thin‐slice high‐resolution multi‐slice spiral CT scan in a supine position, and high‐resolution CT images of all patients were reviewed by a radiologist with > 14 years of experience in chest imaging
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?	Unclear
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
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?	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?	Yes
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Unclear risk