Martín‐Sánchez 2020.

Study characteristics
Patient Sampling	Purpose: diagnosis of SARS‐CoV‐2 infection (mild to severe COVID‐19 disease); to describe the clinical characteristics and 30‐day mortality rates in ED patients with COVID‐19 in different diagnostic groupings Design: cross‐sectional cohort study, retrospective data collection Recruitment: COVID‐19 suspects treated in the emergency room Sample size: n = 1417 (1190 cases) (after exclusion of all participants without an RT‐PCR) Inclusion criteria: all suspicious cases of COVID‐19 served in the ED of the San Carlos Clinical Hospital Exclusion criteria: patients with a positive PCR test prior to assessment in the ED
Patient characteristics and setting	Facility cases: positive RT‐PCR for SARS‐CoV‐2 Facility controls: negative RT‐PCR for SARS‐CoV‐2 Country: Spain Dates: 28 February 2020‐31 March 2020 Symptoms and severity: 30‐day mortality was 11.5% (56.5% in hospitalised cases and 19.6% in cases classified as severe) Demographics: age: controls median 50.7 years, cases median 61.5 years M%/F%: cases 53.5/46.5, controls 37.4/62.6 Exposure history: not specified
Index tests	Cough Dystermic sensation Dyspnoea Thoracic pain Diarrhoea Nausea/vomiting Headache Confusion Anosmia Dysgeusia Myalgia Asthenia Odynofagia Nasal congestion Cutaneous lesions Syncopes Body temperature Pulse Oxygen saturation BP
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: SARS‐CoV‐2 RT‐PCR test (nasal‐ and oropharyngeal swabs)
Flow and timing	Index tests and reference standard both taken at the ED
Comparative
Notes	Strong preselection of participants, unclear why some were not tested, very high disease prevalence 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?	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?			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?	Unclear
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