Comparison of diagnostic accuracies of rapid serological tests and ELISA to molecular diagnostics in patients with suspected COVID-19 presenting to the hospital

Ong, David S.Y.; de Man, Stijn J.; Lindeboom, Fokke A.; Koeleman, Johannes G.M.

OBJECTIVES: To assess the diagnostic performance of rapid lateral flow immunochromatographic assays (LFAs) compared to an enzyme-linked immunosorbent assay (ELISA) and nucleic acid amplification tests (NATs) in suspected coronavirus disease 2019 (COVID-19) patients. METHODS: Patients presenting to a Dutch teaching hospital were eligible between March 17 and April 10, 2020, when they had respiratory symptoms that were suspected for COVID-19. The performances of six different LFAs were evaluated in plasma samples obtained on corresponding respiratory sample dates of NATs testing. Subsequently, the best performing LFA was evaluated in 228 patients and in 50 sera of a historical patient control group. RESULTS: In the pilot analysis sensitivity characteristics of LFA were heterogenous ranging from 2/20 (10%; 95% confidence interval (CI) 0-23) to 11/20 (55%; 95% CI 33-77). In the total cohort, Orient Gene Biotech COVID-19 IgG/IgM Rapid Test LFA had a sensitivity of 43/99 (43%; 95% CI 34-53) and specificity of 126/129 (98%; 95% CI 95-100). Sensitivity increased to 31/52 (60%; 95% CI 46-73) in patients with at least seven days of symptoms, and to 21/33 (64%; 95% CI 47-80) in patients with C-reactive protein (CRP) >100 mg/L. Sensitivity and specificity of Wantai SARS-CoV-2 Ab ELISA was 59/95 (62%; 95% CI 52-72) and 125/128 (98%; 95% CI 95-100) in all patients, respectively, but sensitivity increased to 38/48 (79%; 95% CI 68-91) in patients with at least seven days of symptoms. CONCLUSIONS: There is large variability in diagnostic test performance between rapid LFAs, but overall limited sensitivity and high specificity in acutely admitted patients. Sensitivity improved in patients with longer existing symptoms or high CRP. LFAs should only be considered as additional triage tools when these may lead to the improvement of hospital logistics.