Diagnostic accuracy of LAMP versus PCR over the course of SARS-CoV-2 infection

• Published in: International journal of infectious diseases 2021-06, Vol.107, p.195-200
• Main Authors: Inaba, Masato, Higashimoto, Yuki, Toyama, Yoko, Horiguchi, Tomoya, Hibino, Masaya, Iwata, Mitsunaga, Imaizumi, Kazuyoshi, Doi, Yohei
• Format: Article
• Language: English
• Subjects: Adult; COVID-19; COVID-19 - diagnosis; COVID-19 Nucleic Acid Testing - methods; COVID-19 Testing; Female; Humans; Male; Middle Aged; Molecular Diagnostic Techniques - methods; Nucleic Acid Amplification Techniques - methods; RT-LAMP; RT-qPCR; SARS-CoV-2; Sensitivity; Sensitivity and Specificity; Specificity
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2021.04.018

•We compared sensitivities and specificities of the SARS-CoV-2 RT-LAMP with RT-qPCR.•Up to the 9th day of onset, RT-LAMP has the same diagnostic sensitivity as RT-qPCR.•After the 10th day of onset, the positivity of RT-LAMP decreased considerably.•The limit of detection of RT-LAMP was 6.7 SARS-CoV-2 RNA copies/reaction. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) has been validated to diagnose several viral infections. However, its diagnostic accuracy in detecting SARS-CoV-2 in real-life clinical settings remains unclear. This study aimed to determine the diagnostic sensitivity and specificity of RT-LAMP compared to reverse transcription-quantitative polymerase chain reaction (RT-qPCR) over the disease course of COVID-19. A total of 124 nasopharyngeal swab samples obtained from 24 COVID-19 patients were tested by RT-LAMP and RT-qPCR. Sensitivities and specificities of RT-LAMP compared with RT-qPCR were analyzed as a function of time from onset. Up to the 9th day after onset, the RT-LAMP had a positivity of 92.8%, and the sensitivity and specificity compared with RT-qPCR was 100%. However, after the 10th day after onset, the positivity of RT-LAMP decreased to less than 25%, and the concordance of positivity between the two methods was below 60%. The limit of detection of RT-LAMP was 6.7 copies/reaction. Until the 9th day after the onset of symptoms, RT-LAMP had the same diagnostic accuracy as RT-qPCR. These findings suggest that RT-LAMP can be used as a diagnostic tool for COVID-19 as an alternative to RT-qPCR in the acute symptomatic phase of COVID-19.