Assessment of a laboratory-based SARS-COV-2 antibody test among hemodialysis patients: A quality improvement initiative

ABSTRACT

Background: The coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Assessment of newly developed anti-SARS-CoV-2 antibody tests in hemodialysis patients is needed. Methods: As part of a quality improvement (QI) initiative, nasopharyngeal swabs and predialysis blood samples were collected on the same day from adults receiving routine dialysis care at clinics managed by a large dialysis organization in the Miami, Florida, region (April 23-30, 2020). Polymerase chain reaction (PCR) tests for SARS-CoV-2 (Fulgent Genetics, Temple City, California) and chemiluminescence immunoassays (Diazyme Laboratories, Inc, Poway, California) were performed according to manufacturer protocols. For antibody tests (IgM and IgG), a reading of >;1 arbitrary unit/ mL was scored as positive. Results: Of 715 participants in the QI initiative, 38 had symptoms consistent with COVID-19 prior to or during the initiative. Among these, COVID-19 was confirmed in 14 and ruled out in 20, with 4 being inconclusive. Among the 34 patients with known COVID-19 status, the sensitivity and specificity of the antibody test were 57.1% and 85.0%, respectively, when both IgM and IgG were considered. The remaining 677 patients had no record of symptoms consistent with COVID-19 or any known exposure. Of these, 38 (5.6%) tested positive for anti-SARS-CoV-2 antibodies;none of the antibody-positive patients with available PCR results (N=33) tested positive for SARS-CoV-2. Conclusions: The operational characteristics of the laboratory-based antibody test make it sufficient to rule in, but not rule out, SARS-CoV-2 infection in the appropriate clinical circumstance. A substantial proportion of dialysis patients may have had asymptomatic SARS-CoV-2 infection.