Diagnostic and prognostic role of the SARS-COV-2-specific IgA antibody: an updated systematic review and meta-analysis

OBJECTIVE:This systematic review and meta-analysis aimed to investigate the diagnostic accuracy and prognostic role of the SARS-CoV-2-specific IgA antibody. METHODS:A computerized search was conducted on MEDLINE, Scopus, Web of Science, Cochrane Library, and Google Scholar, using the relative keywords. Received citations were screened, and relevant data were extracted from the included studies. The methodological quality of the articles was assessed through modified version of the quality assessment of diagnostic accuracy studies tool-2. To analyze the risk of bias, four domains were reviewed: patient selection, index test, reference standard and flow & timing; three domains, patient selection, index test, and reference standard, were assessed based on applicability. Review Manager-5.4 and Meta-DiSc were used for analysis. RESULTS:Twenty-nine studies were included in the qualitative synthesis, and only 15 studies were included in the quantitative synthesis. On pooled analysis, the overall sensitivity of IgA was 90% (87% to 92%), specificity 94% (92% to 95%), positive likelihood ratio (LR) 9.33 (3.40 to 25.57), negative LR 0.14 (0.05 to 0.37), diagnostic Odds Ratio 71.5 (13.22 to 382.80), and overall area under the curve was 96.5%. Overall random effect estimate demonstrated a significant elevation of IgA in the severe group [standardized mean difference=0.23, 95% CI 0.10 to 0.36), p=0.0005], compared to non-severe group. CONCLUSION:The current evidence suggests that IgA has good sensitivity, specificity, and accuracy in detecting patients with COVID-19 along with the clinical and laboratory characteristics. The prognostic role of IgA needs more comprehensive investigations on larger samples to reach conclusive evidence.