Nobel 2020.

Study characteristics
Patient Sampling	Purpose: assess GI symptoms in COVID‐19 and their association with short‐term outcomes Design: diagnostic case‐control, retrospective study Recruitment: adults who underwent nasopharyngeal swab testing for SARS‐CoV‐2 at outpatient settings: clinics or the ED, of New York‐Presbyterian‐Columbia or the medical centre's affiliates in New York Sample size: 516 (278 cases) Inclusion criteria: adults ≥ 18 years of age who underwent nasopharyngeal swab testing for SARS‐CoV‐2. Indications for testing during this period were respiratory symptoms (cough, fever, shortness of breath) with intent to hospitalise or the same symptoms in essential personnel. Exclusion criteria: if insufficient data were available in the electronic medical record or if testing was performed during a pre‐existing inpatient admission
Patient characteristics and setting	Facility cases: SARS‐CoV‐2 PCR test result positive (1 test) Facility controls: SARS‐CoV‐2 PCR test result negative Country: USA Dates: 10 March 2020‐21 March 2020 Symptoms and severity: respiratory symptoms (cough, fever, shortness of breath) with intent to hospitalise or in essential workers Demographics: median age: 51‐70 years (cases and controls), gender distribution: cases (M/F(%): 52/48), controls (M/F(%): 45/55) Exposure history: not specified
Index tests	GI symptoms: diarrhoea, vomiting/nausea
Target condition and reference standard(s)	TC: SARS‐Cov‐2 infection RS: SARS‐CoV‐2 PCR test, once (nasopharyngeal swab)
Flow and timing	Time interval: both taken at intake
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?	No
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?		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