Zhu 2020b.

Study characteristics
Patient Sampling	Purpose: description of initial clinical features in patients with suspected and confirmed SARS‐CoV‐2 infection Design: cross‐sectional, retrospective study Recruitment: all patients with suspected COVID‐19 who presented to the ED of the First Affiliated Hospital of USTC and the Infectious Hospital of the First Affiliated Hospital of USTC for the first time Sample size: n = 116 (32 cases) Inclusion criteria: patients defined as suspected SARS‐CoV‐2 infection based on guidelines for the diagnosis and treatment of pneumonia caused by novel coronavirus infection (trial version III) presentation to, clinical observation and quarantine in our ED nucleic acid amplification test performed in the ED Exclusion criteria: transfer from another hospital or previous visit to our hospital and previous diagnosis of COVID‐19
Patient characteristics and setting	Facility cases: positive nucleic acid amplification test on admission or 24 h later Facility controls: SARs‐CoV‐2 PCR test negative Country: China, Anhui Dates: 24 January 2020‐20 February 2020 Symptoms and severity: all suspected COVID‐19 patients included; days since onset of symptoms median 5 (IQR 2‐7) Demographics: median age: all: 40 years (IQR 27‐53), cases: 46 years (IQR 35‐52), controls: 35 years (IQR 27‐53); gender distribution M%/F%: all 46/54, cases 47/53, controls 46/54 Exposure history: no specific exposure history common to all patients with suspected disease: 8 (25%) diagnosed patients had visited Wuhan in the previous 2 weeks and 12 (38%) had been exposed to patients with infection in the previous 2 weeks
Index tests	Fever Cough Myalgia or fatigue Experctoration Chest stuffiness (congestion) Haemoptysis Headache Diarrhoea
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: nucleic acid amplification test not further specified (twice in case negatives) (samples: swabs, origin not specified)
Flow and timing	Index tests and RS both taken on admission or after 24 h
Comparative
Notes
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?	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?	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?		Unclear risk

BP: blood pressure; COPD: constructive obstructive pulmonary disease; COVID‐19: coronavirus disease 2019; CT: computed tomography; ED: emergency department; F: female; FiO₂: fraction of inspired oxygen; GI: gastrointestinal; ICU: intensive care unit; IgM: immunoglobulin M;IQR: interquartile range; M: male; NCP: novel coronavirus pneumonia; OTD: olfactory and taste disorder; PaO₂: partial pressure of oxygen; RS: reference standard; RT‐PCR: reverse transcription polymerase chain reaction; SARS‐CoV‐2: severe acute respiratory syndrome coronavirus 2; SD: standard deviation;SpO₂: oxygen saturation; TC: target condition; WBC: blood white blood cell; WHO: World Health Organization; 2019‐nCoV: 2019 novel coronavirus