Zhang 2020.

Study characteristics
Patient Sampling	COVID‐19 cases: hospitalized patients from Zhongnan Hospital of Wuhan university. COVID‐19 was diagnosed based on criteria issued by the National Health Commission of China. Controls: CAP hospitalized in Department of Respiratory and Critical Care Medicine between 22 January‐22 February 2019. 5 control patients with chronic Hepatitis B or cirrhosis were excluded
Patient characteristics and setting	Setting: infectious diseases department hospital; controls in pulmonary and critical care departments Site: Department of Infectious Disease, Zhongnan Hospital of Wuhan University Country: China Demographics: 4 participants < 14 years of age; of the 115 participants in the COVID‐19 group, 49 (42.60%) were male and 66 (57.40%) were female. Mean age at diagnosis was 49.52 ± 17.06 years (IQR, 35‐62; range, 20‐86 years). The CAP group included 55 (48.25%) male participants and 59 (51.75%) female participants, mean age 61.11 ± 18.84 years (IQR, 47‐76; range, 18‐89 years). Severity: 2 patients with chronic Hepatitis B were excluded, and 115 patients were included to COVID‐19 group; from the controls group, four patients with Hepatitis B or cirrhosis were excluded.
Index tests	Routine laboratory tests: ALT, AST, total BIL, ALP, GGT, LDH, ALB, GLB, INR, CRP
Target condition and reference standard(s)	COVID‐19 was diagnosed based on criteria issued by the National Health Commission of China; includes RT‐PCR once, Clinical signs and symptoms, chest CT Controls: CAP
Flow and timing	Not reported
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?	No
Did the study avoid inappropriate exclusions?	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?	Unclear
If a threshold was used, was it pre‐specified?	Unclear
Could the conduct or interpretation of the index test have introduced bias?		Unclear 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?	No
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?		High 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?	Unclear
Were all patients included in the analysis?	Unclear
Could the patient flow have introduced bias?		Unclear risk