Prospective study of 1308 nasopharyngeal swabs from 1033 patients using the LUMIPULSE SARS-CoV-2 antigen test: Comparison with RT-qPCR

Abstract

Background Reverse-transcription PCR (RT-PCR) is the gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection. Previously, we demonstrated the accuracy of the quantitative LUMIPULSE SARS-CoV-2 antigen test using samples collected retrospectively. Here, the antigen test was clinically validated using prospective samples. Methods A total of 1,033 nasopharyngeal swab samples were collected 1,033 individuals and an additional 275 follow-up samples were collected from 43 patients who later tested positive for COVID-19. All 1,308 samples were subjected to quantitative RT-PCR (RT-qPCR) and the LUMIPULSE antigen test. Antibody response was investigated for patients with discordant results to clarify whether seroconversion had occurred. Results RT-qPCR identified 990 samples as negative and 43 as positive, while the antigen test identified 992 as negative, 37 as positive, and 4 as inconclusive. The overall concordance rate was 99.7% (1,026/1,029). The sensitivity, specificity, positive predictive value and negative predictive value of the antigen test were 92.5% (37/40), 100% (989/989), 100% (37/37) and of 99.7% (989/992), respectively, after excluding the four inconclusive results. The kappa coefficient was 0.960 (95% confidence interval, 0.892‐0.960), suggesting excellent agreement between the two tests. The seropositive in five out of the seven patients with discordant results suggested that the discrepancy was caused by samples collected during the late phase of infection. Using the follow-up samples, we observed a correlation between the antigen level and the viral load or threshold cycle (Ct) value. The concordance rate between these test results tended to be high among samples collected up to 9 days after symptom onset but this gradually decreased thereafter. Conclusions This prospective study demonstrated that the LUMIPULSE antigen test is a highly accurate diagnostic for SARS-CoV-2.

Comparison of Roche and Lumipulse quantitative SARS-CoV-2 antigen test performance using automated systems for the diagnosis of COVID-19

“…Positive correlations were observed between the Roche COI value and viral load (R 2 = 0.805) and between the Roche COI value and Ct value (R 2 = 0.815) (Figure 2(A)). Similarly, positive correlations were observed between Lumipulse Ag level and viral load (R 2 = 0.837) and between Lumipulse Ag level and Ct value (R 2 = 0.851) (Figure 2(B)), as we previously reported (Hirotsu et al, 2021).…”

“…The Ag levels were determined quantitatively with the Lumipulse SARS-CoV-2 Ag test (Fujirebio, Inc., Tokyo, Japan) as we previously reported (Hirotsu et al, 2021;Hirotsu et al, 2020b). In brief, 700 mL of the VTM samples were briefly vortexed, transferred into a sterile tube, and centrifuged at 2000 Â g for 5 min.…”

“…We previously evaluated the accuracy of the Lumipulse antigen (Ag) test, an automated system that quantitatively measures nucleocapsid Ag using a chemiluminescent enzyme immunoassay (Hirotsu et al, 2021;Hirotsu et al, 2020b). The proportion of samples with positive results using the Lumipulse Ag test decreased rapidly around nine days after the onset of symptoms (Hirotsu et al, 2021), suggesting that this assay may be suitable for diagnosing COVID-19 patients when infectious viruses are present. Recently, Roche launched another Ag test platform for detecting nucleocapsid Ag.…”

Diagnostic Performance and Characteristics of Anterior Nasal Collection for the SARS-CoV-2 Antigen Test: A Prospective Study in Japan

“…In the current study, anterior nasal samples provided a lower antigen test sensitivity than our previous study evaluating nasopharyngeal samples (3). The sensitivity of antigen tests is largely influenced by the viral load in collected samples (9)(10)(11)(12). The QuickNavi-COVID19 Ag test could detect SARS-CoV-2 in almost all samples with Ct values < 30, and in 18.8% of samples with Ct values > 30 (3).…”

Diagnostic performance and characteristics of anterior nasal collection for the SARS-CoV-2 antigen test: a prospective study

“…Nevertheless, this lower sensitivity of 72.5% may be acceptable since according to the reported systematic review, sensitivity of nasal swab was 86% in comparison to nasopharyngeal swab by RT-PCR 9 . The sensitivity of antigen tests is largely influenced by the viral load in collected samples 10 – 13 . The QuickNavi-COVID19 Ag test could detect SARS-CoV-2 in almost all samples with Ct values < 30, and in 18.8% of samples with Ct values > 30 3 .…”