Concordance of andquot;Rapidandquot; Serological Tests and IgG and IgM Chemiluminescence for SARS-COV-2

Abstract

Objectives: To evaluate a sample of immunofluorescent and immunochromatographic tests used in Ecuador to show their agreement in relation to Chemiluminescence. Setting: Primary care limitations for a sample of “rapid test” assays used for serological diagnosis of SARS-CoV-2 in Ecuador, South-America. Participants: A diagnostic test evaluation assay was performed to establish the performance of five “rapid” tests for IgG and IgM serology for SARS-CoV-2 using a panel of 30 serum samples from routine patients. Interventions: For the evaluation of clinical performance, the qualitative results of the tests were compared against those obtained by chemiluminescence, dichotomized as positives (>10 AU/mL) or negative (<10 UA/mL). Primary and secondary outcome measures: Demonstration of agreement in defining the subjects with the dichotomous criterion (positive or negative for SARS-CoV-2 antibodies), calculating complex repeatability, positive agreements and negative agreements, with their corresponding 95% confidence interval and Cohen's Kappa test. Results: The best agreement is seen in the immunofluorescent assay, for the IgG contrast, with a particularly good kappa index (0.85), without positive disagreements and a negative disagreement of about 15%. In the immunochromatographic methods Kappa index was 0.61 at best, with disagreements in negative findings of ≈35% and in positive cases of up to ≈70%. Conclusions: Given the high demand and supply in the market of rapid serological tests, its evaluation against panels of serologically positive or negative samples established by Chemiluminescence or Electro chemiluminescence is essential to authorize its extensive use in populations.