Liang 2020.

Study characteristics
Patient Sampling	Purpose: to estimate the prevalence of COVID‐19 in pneumonias during this period and to find the unique features of COVID‐19 as compared to pneumonias caused by other agents Design: cross‐sectional, single‐centre, retrospective study Recruitment: 342 cases of pneumonia were diagnosed in Fever Clinic in Peking University Third Hospital. From these patients, 88 were reviewed by panel discussion as possible or probable cases of COVID‐19, and received 2019‐nCoV detection by RT‐PCR Sample size: n = 88 (21 cases) Inclusion criteria: patients visiting the Fever Clinic at Peking University Third Hospital. Based on epidemiological history, epidemiological evidence, fever and/or respiratory symptoms, chest radiological findings and WBC results, cases with possible or probable COVID‐19 were sent for panel discussion and then for 2019‐nCoV detection by RT‐PCR Exclusion criteria: COVID‐19 unlikely by panel discussion; lack of CT scan or no signs of pneumonia on CT scan; paediatric patients
Patient characteristics and setting	Facility cases: 2019‐nCoV real‐time PCR testing, which was positive in 19 cases (confirmed cases). In another 2 patients, though PCR testing was negative, a clinical diagnosis was made according to epidemiological evidence, consistent clinical and CT findings (clinical cases) Facility controls: for the cases with negative viral detection, the diagnosis of COVID‐19 was excluded based on inconsistent epidemiological, clinical or radiological data Country: China Dates: 21 January 2020‐15 February 2020 Symptoms Fever with a mean body temperature of 37.8 C Cough Expectoration Fatigue Headache Dizziness Shortness of breath Myalgia or arthralgia Sore throat Nasal symptoms and diarrhoea Severity of COVID‐19 Mild‐moderate: fever and/or respiratory symptoms with pneumonia in radiology examination, without signs of severe or very severe diseases Severe: presence of 1 of the following: respiratory rate ≥ 30 beat/min; SpO2 ≤ 93% at rest; PaO2/FiO2 ≤ 300 mmHg Very severe: presence of 1 of the following: severe respiratory failure requiring mechanical ventilation; shock; complicated with other organ failure and requiring ICU admission Demographics: COVID‐group only: median age was 42.0 years (25th‐75th percentile, 34.5‐66.0 years). Range 24‐85. Male/female: 11 (52.4%)/10 (47.6%) Exposure history: 19/21 (90.5%) had a clear epidemiological history of COVID‐19. 7 patients, from 5 family clusters, had close contact with their family members
Index tests	Fever with a mean body temperature of 37.8 C Cough Expectoration Fatigue Headache Dizziness Shortness of breath Myalgia or arthralgia Sore throat Nasal symptoms and diarrhoea
Target condition and reference standard(s)	TC: COVID‐19 pneumonia RS: 2019‐nCoV real‐time PCR testing or clinical diagnosis was made according to epidemiological evidence, consistent clinical and CT findings
Flow and timing	Time interval not specified
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?	Unclear
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	No
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?	No
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?	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?		High risk