Song 2020b
Study characteristics
Patient Sampling  Purpose: to develop a tool for early diagnosis of SARS‐CoV2‐infected patientsDesign: cross‐sectional, retrospective, single‐centre (2 time frame study: training ‐ validation data set)Recruitment: 1311 patients who presented to the First Affiliated Hospital, School of Medicine, Zhejiang University with at least 1 SARS‐CoV‐2 RT‐PCR testSample size: n = 304 (73 cases) (= subset of the study including training dataset only)n = 95 (18 cases) (= validation dataset)Inclusion criteriaAll RT‐PCR‐positive cases; 1311
All RT‐PCR‐negative patients who came to the First Affiliated Hospital, School of Medicine, Zhejiang University and performed with at least 1 SARS‐CoV‐2 nucleic acid detection for analysis RT‐PCR
First 60% of negative outpatients sorted by 'Z‐A' based on Chinese first name from Qingchun District (training dataset), and then final 40% who presented (validation dataset)
Exclusion criteriaAsymptomatic patients without history of exposure but had strong willingness for detection
Patients with "important" missing data
Patient characteristics and setting  Facility cases: positive SARS‐CoV‐2Facility controls: negative SARS‐CoV‐2Country: ChinaDates: 20 January 2020‐05 February 2020Symptoms and severity: in positives: non‐severe (n = 31), including mild or moderate patients to severe (n = 42) including severe or critical patientsMild: patients had no pneumonia on imaging (CT)
Moderate: patients with symptoms and imaging examination showing pneumonia
Severe: patients meet any of the following:
respiratory rate ≥ 30/min
resting pulse SpO2 ≤ 93%
PaO2/FiO2 ≤ 300 mmHg (1 mmHg = 0.133 kPa)
multiple pulmonary lobes showing more than 50% progression of lesion in 24‐48 hours on imaging
Critical: patients meet any of the following:
respiratory failure requiring mechanical ventilation
shock
combination of other organ failure that requires admission to ICU
Demographics: M/F: cases 46/27, controls 104/127
median age: cases 53.0 years (43.5‐62.0) controls 34 years (29‐49)Exposure history: Wuhan‐related exposure and or close contact to confirmed COVID‐19 case: cases 40.7%, controls 57.5%
Index tests  Fever
Cough
Expectoration
Headache
Myalgia or fatigue
Chill
Rhinobyon/rhinorrhoea
Pharyngalgia
Dyspnoea
Diarrhoea
Nausea/vomiting
Temperature (maximum)
Body temperature
SpO2
Respiratory rate
Heart rate
Mean arterial pressure
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: RT‐PCR for SARS‐CoV‐2 (test not specified: "using emergency use authorization approved SARS‐CoV‐2 assays)" (following WHO protocol, 2 target RT‐PCR (ORF1 and N)
Flow and timing  Within 3 h for RS, first in‐hospital stay for index tests
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?  No      
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?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Yes      
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