Perez‐Garcia 2021 [A].

Study characteristics
Patient Sampling	Purpose: Diagnosis of acute infection; compare the diagnostic performance of six serologic tests for the detection of antibodies against SARS‐CoV‐2 Design: Two‐group study, to assess sensitivity and specificity [1] Confirmed COVID‐19 (n = 80) [2] Pre‐pandemic control group (other diseases) (n = 60) Recruitment: [1] Unclear [2] Randomly selected group of patients with a sample taken for other serologic studies, from September 1 to November 30, 2019. Prospective or retrospective: Retrospective Sample size: 140 (80) Further detail: Inclusion: [1] Symptomatic patients admitted to the Emergency department between March 1 and April 28, 2020, with suspicion of COVID‐19 and confirmation by PCR [2] Patients with a sample taken for other serologic studies Exclusion ‐ not stated
Patient characteristics and setting	Setting: Emergency department Location: Hospital Universitario Príncipe de Asturias, Madrid Country: Spain Dates: Cases ‐ 2020‐03‐01 to 2020‐04‐28 Symptoms and severity: All cases were symptomatic. Severity not stated Demographics: Not stated Exposure history: Not stated Non‐Covid group 1: COVID‐negative Source: Pre‐pandemic stored serum samples 2019‐09‐01 to 2019‐11‐30 Characteristics: Sample taken for other serologic studies; 32 female, 28 male; mean age 48 years (median 44 years, range 18‐88 years) Rheumatoid arthritis: n = 5; psychiatric disorder: n = 3; psoriasis: n = 1; pregnancy: n = 6; mycosis fungoides: n = 1; multiple sclerosis: n = 1; lung cancer: n = 1; HIV infection: n = 2; haemodialysis: n = 5; HCV infection: n = 1; COPD, lung cancer: n = 1; chronic kidney disease: n = 1; breast cancer: n = 1; acute myeloid leukaemia: n = 1; acute lymphoid leukaemia: n = 1; no main underlying condition: n = 29
Index tests	Test name: [A] Hangzhou Alltest ‐ 2019‐nCoV IgG/IgM [B] Innovita Biological ‐ 2019‐nCoV Ab test [C] Epigentek SeroFlash IgM/IgG [D] DiaPro COVID‐19 IgG Confirmation [E] Roche ‐ Elecsys anti‐SARS‐CoV‐2 Ab [F] Siemens Atellica Total‐Ab assay Manufacturer: [A] Hangzhou Alltest [B] Innovita Biological [C] Epigentek [D] DiaPro [E] Roche [F] Siemens Antibody: [A] to [D] IgG and IgM [E] [F]Total antibodies Antigen target: [A] N‐based, [B] N and S based, [C] N and S based, [D] N and S based, [E] N based, [F] Total antibodies Evaluation setting: [A] [B] [C] POCT performed retrospectively in lab [D] [E] [F] Laboratory Test method: LFA ‐ [A][B][C] ELISA ‐ [D] CLIA ‐ [E] [F] Timing of samples: 0‐7 days from onset of symptoms n = 18 8‐14 days from onset of symptoms n = 21 > 14 days from onset of symptoms n = 41 Samples used: Serum Test operator: Not stated Definition of test positivity: Positive serologic result was defined for LFA and ELISA tests for samples that resulted positive for either IgM or IgG antibodies. [A] [B] [C] visual‐based [D] [E] [F] Cut‐off not stated Blinding reported: Not stated Threshold predefined: [A] [B] [C] yes [D] [E] [F] Not stated
Target condition and reference standard(s)	Reference standard: RT‐PCR, threshold not stated Samples used: Not stated Timing of reference standard: Not stated Blinded to index test: Yes, based on timing Incorporated index test: No Definition of non‐COVID cases: Pre‐pandemic Samples used: None Timing of reference standard: Pre‐pandemic Blinded to index test: Yes, based on timing Incorporated index test: No
Flow and timing	Time interval between index and reference tests: Not stated Study period and patient enrolment period almost identical All patients received same reference standard: No [1] PCR [2] Pre‐pandemic Missing data: yes, sensitivity evaluation of CLIA techniques could only be performed with 50 samples due to insufficient sample volume. 41 samples > 14 days pso not eligible for our review Uninterpretable results: Not stated Indeterminate results: Excluded from the analysis Two samples presented indeterminate result for IgG or IgM and were excluded from the analysis. Unit of analysis: Patients
Comparative
Notes	Funding: None Publication status: Published paper Source: Journal of Virological Methods Author COI: None declared
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?	No
Were all patients included in the analysis?	Yes
Did all participants receive a reference standard?	Unclear
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk