Detecting SARS-CoV-2 at Point of Care: Preliminary Data Comparing Loop-Mediated Isothermal Amplification (LAMP) to PCR
9 Pages Posted: 31 Mar 2020 Last revised: 1 Apr 2020
Date Written: March 31, 2020
Background: The need for a fast and reliable test for COVID-19 is paramount in managing the current pandemic. A cost effective and efficient diagnostic tool as near to the point of care (PoC) as possible would be a game changer in current testing. We tested reverse transcription loop mediated isothermal amplification (RT-LAMP), a method which can produce results in under 30 minutes, alongside standard methods in a real-life clinical setting.
Methods: This service improvement project piloted a research RT-LAMP method on nasal and pharyngeal swabs on 21 residents in an NHS Category 1 care home, with two index COVID-19 cases, and compared it to multiplex tandem reverse transcription polymerase chain reaction (RT-PCR). We calculated the sensitivity, specificity, positive and negative predictive values of a single RT-LAMP swab compared to RT-PCR, as per STARD guidelines. We also recorded vital signs of patients to correlate clinical and laboratory information.
Findings: The novel method accurately detected 8/10 PCR positive cases and identified a further 3 positive cases. Eight further cases were negative using both methods. Using repeated RT-PCR as a “gold standard”, the sensitivity and specificity of the novel test were 80% and 73% respectively. Positive predictive value (PPV) was 73% and negative predictive value (NPV) was 83%. We also observed hypothermia to be a significant early clinical sign in a number of COVID-19 patients in this setting.
Interpretation: RT-LAMP testing for SARS-CoV-2 was found to be promising, fast, easy to use and to work equivalently to RT-PCR methods. Definitive studies to evaluate this method in larger cohorts are underway. RT-LAMP has the potential to transform COVID-19 detection, bringing rapid and accurate testing to the point of care. This method could be deployed in mobile testing units in the community, care homes and hospitals to detect disease early and prevent spread.
Note: Funding: CJS is supported by HEFCE funding. No other funding was sought for this study.
Conflict of Interest: CJS is supported by HEFCE funding. CS and SW are employees of MicrosensDX Ltd. Testing was provided free of charge by MicrosensDx. PCR tests were performed as part of routine clinical care. No other funding was sought for this study. Other authors report no conflict of interest.
Ethical Approval: This project was a clinical service improvement and as such did not require REC approval. All capacitous participants and relatives in case of non-capacitous were appraised of the project and given the opportunity to not take part.
Keywords: COVID-19, point of care, LAMP, COVID-19 diagnostics, SARS-CoV-19
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