Rapid and accurate diagnosis of pulmonary tuberculosis using TB-LAMP assay in Northern India patients

Abstract Tuberculosis (TB) is the world’s top infectious killer, especially in underdeveloped and developing countries. More sensitive, rapid, and cost-effective diagnostic tool for pulmonary tuberculosis (PTB) remains a challenge in resource limited and rural regions. In 2016, WHO approved TB-LAMP (loop mediated isothermal amplification) assay as a replacement for smear microscopy for diagnosis of PTB in adult TB suspects. However, more diverse epidemiological and clinical research should be conducted to support the deployment of the TB-LAMP program in peripheral level healthcare settings. This study analyzed the diagnostic efficacy of a quick and inexpensive TB-LAMP for the diagnosis of PTB in tuberculosis endemic Delhi-NCR Indian population. A retrospective analysis was performed on 439 cases from October 2021 to May 2022; at the National Institute of Tuberculosis and Respiratory Diseases, Hospital. The samples were accessed by PTB-site smear microscopy, Multiplex TB PCRs for IS6110 & MPB64, GeneXpert and LAMP assay. It was observed that TB-LAMP assay displayed 1.8 fold (minimum 49.2%) higher positivity rates than smear microscopy test (maximum 29.6%). In comparison to the composite reference standard, TB-LAMP assay was established to be 84.3% sensitive and 96.8 % specific for diagnosis of adult PTB samples. The positive predictive value (PPV), and negative predictive value (NPV) of the TB-LAMP assay were 88.2 (95%CI: 77.3-94.3) and 95.6 (95%CI: 94.2-96.7) respectively. Our research concluded TB-LAMP assay as essential point-of-care test as a replacement of sputum smear microscopy for diagnosis of PTB in adults suspected cases, particularly in resource-limited and rural health care settings.