Decru 2020 [A].

Study characteristics
Patient Sampling	Purpose: Assessment of clinical performance of multiple rapid tests for diagnosis of convalescent‐phase COVID‐19 infection Design: Two‐group study estimating both sensitivity and specificity Group [1]: PCR‐confirmed COVID‐19 cases (n = 26 patients, 33 samples) Group [2]: PCR‐negative patients without clinical suspicion of COVID‐19 (n = 39 patients/samples) Recruitment: Unclear Prospective or retrospective: Retrospective Sample size: 72 (33) Further detail: No more details available
Patient characteristics and setting	Setting: Unclear Location: University Hospitals, Leuven Country: Belgium Dates: Not stated Symptoms and severity: All symptomatic individuals. No further details available (table footnote described one patient as having fever and compatible CT but no respiratory symptoms) Demographics: Age, median (IQR): 67 y (33‐92 y) Exposure history: Not stated Non‐Covid group 1: Group [2]: PCR‐negative patients without clinical suspicion of COVID‐19 Source: Not stated; negative PCR was within previous 7 days Characteristics: Not stated
Index tests	Test name: [A] MultiG single lane (MultiG1, lot NCP‐20030181) [B] MultiG dual lane (MultiG2, lot COV1452003C) [C] COVID‐19 IgM/IgG Rapid Test Cassette (lot 2003318) [D] COVID‐19 Coronavirus Rapid Test Cassette (lot COV20030120) Manufacturer: [A], [B]: Multi‐G, Belgium [C]: Orient Gene Biotech, China [D]: SureScreen Diagnostics Antibody: IgG and IgM Antigen target: Not stated Evaluation setting: All POC tests, but likely done in lab Test method: All lateral flow immunoassays (LFA) Timing of samples: 23‐65 days after symptom onset; (data by week provided by authors) day 23‐28: 3, 9% day 29‐35: 5, 14% day > 35: 25, 71% Samples used: Whole blood, plasma Test operator: Not stated Definition of test positivity: Not stated (but likely visual‐based) Blinding reported: Unclear Threshold predefined: Visual line
Target condition and reference standard(s)	Reference standard: RT‐PCR test (no further details available) Samples used: Not stated Timing of reference standard: Not stated Blinded to index test: Yes (done earlier) Incorporated index test: No Definition of non‐COVID cases: RT‐PCR test (no further details available) Samples used: Not stated Timing of reference standard: Test done in the last 7 days before enrolment in the study Blinded to index test: Yes (done earlier) Incorporated index test: No
Flow and timing	Time interval between index and reference tests: 21‐62 days from first RT‐PCR‐positive All patients received same reference standard: Yes (for the purpose of this item we considered any RT‐PCR to be adequate and 'the same') Missing data: None reported Uninterpretable results: None reported Indeterminate results: None reported Unit of analysis: Samples
Comparative
Notes	Funding: The authors declared no specific funding was received. Publication status: Published letter Source: Clinical Chemistry & Laboratory Medicine Author COI: Authors stated no conflict of interest.
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?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
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)
DOMAIN 2: Index Test (Antibody 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?	Yes
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?			Unclear
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
The reference standard does not incorporate the index test	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?			High
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?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk