Diagnostic accuracy of a point-of-care antigen test for SARS-CoV-2 and influenza in a primary care population (RAPTOR-C19).
Fanshawe TR., Tonner S., Turner PJ., Cogdale J., Glogowska M., De Lusignan S., Okusi C., Perera R., Sebastianpillai P., Williams A., Zambon M., Nicholson BD., Hobbs FDR., Hayward GN., RAPTOR-C19 STUDY GROUP None.
OBJECTIVES: Limited evidence exists for the diagnostic performance of point-of-care tests for SARS-CoV-2 and influenza in community healthcare. We carried out a prospective diagnostic accuracy study of the LumiraDx™ SARS-CoV-2 & influenza A/B assay in primary care. METHODS: 913 adults and children with symptoms of current SARS-CoV-2 infection were recruited from 18 UK primary care practices during a period when Omicron was the predominant COVID variant of concern (June-December 2022). Trained healthcare staff performed the index test, with diagnostic accuracy parameters estimated for SARS-CoV-2 and influenza against real-time reverse-transcription PCR (rtRT-PCR). RESULTS: 151/887 participants were SARS-CoV-2 rtRT-PCR positive, 109 positive for Influenza A, 6 for Influenza B. Index test sensitivity for SARS-CoV-2 was 80.8% (122/151, 95%CI 73.6-86.7%) and specificity 98.9% (728/736, 95%CI 97.9-99.5%). For influenza A, sensitivity was 61.5% (67/109, 95%CI 51.7-70.6%) and specificity 99.4% (771/776, 95%CI 98.5-99.8%). Sensitivity to detect SARS-CoV-2 and influenza dropped sharply at rtRT-PCR cycle thresholds (Ct) >30. CONCLUSIONS: The LumiraDx™ SARS-CoV-2 & influenza A/B assay had moderate sensitivity for SARS-CoV-2 in symptomatic patients in primary care, with lower performance with high rtRT-PCR Ct. Negative results in this patient group cannot definitively rule-out SARS-CoV-2 or influenza.