The novel reverse transcription loop-mediated isothermal amplification (RT-LAMP) method may transform coronavirus disease 2019 (COVID-19) testing by providing rapid and accurate point of care (PoC) testing, according to a study recently published in BMC Infectious Diseases.

The current gold standard method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is multiplex tandem reverse transcription polymerase chain reaction (RT-PCR). The novel RT-LAMP method was developed as a rapid, reliable, and cheaper method that can produce results in under 30 minutes. This prospective service improvement process tested RT-LAMP alongside standard methods in detecting SARS-CoV-2 in a real-life setting.

In total, 21 patients in a high-dependency care home were included. The median age of patients was 76 years (range, 52-89 years) and 70% were women. The RT-LAMP method was performed on deep nasal swabs and the RT-PCR method was performed on both pharyngeal and deep nasal swabs. A positive COVID-19 case was defined as a positive RT-PCR on 1 of 2 tests at Day 3 or 4; a negative COVID-19 case was defined as a negative on both tests. Study authors calculated and compared the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a single swab using RT-LAMP and RT-PCR.

Results suggest RT-LAMP testing for SARS-CoV-2 is equivalent to RT-PCR. In total, 13 patients tested positive for COVID-19 over time. The first 2 patients were confirmed by RT-PCR on day 2. RT-LAMP detected its first positive SARS-CoV-2 patient on day 4. On day 4, 13 total patients were confirmed: 8 were confirmed by both RT-PCR and RT-LAMP, 2 were detected by PT-PCR only, and 3 were detected by RT-LAMP only. The 3 patients detected by RT-LAMP only were initially identified as low positive using RT-LAMP and negative on RT-PCR. All 3 patients remained well at Day 10 with no other explanation for symptoms, such as upper respiratory or urinary tract symptoms. Repeat RT-LAMP tests on the samples from these 3 low positive patients were negative on Day 9.


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RT-LAMP on a single test has 80% sensitivity, 73% specificity, 73% PPV, and 80% NPV. RT-LAMP on 2 tests has 80% sensitivity, 100% specificity, 100% PPV, and 85% NPV.

“Our study is the first ‘real world’ study comparing the effectiveness of RT-PCR and RT-LAMP testing in a group of patients at high risk for COVID-19 and represents an important progression to clinical use for this novel SARS-CoV-2 testing method,” the study authors concluded.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Österdahl MF, Lee KA, Lochlainn MN, et al. Detecting SARS-CoV-2 at point of care: preliminary data comparing loop-mediated isothermal amplification (LAMP) to polymerase chain reaction (PCR). BMC Infect Dis. Published online October 20, 2020. doi: 10.1186/s12879-020-05484-8.