Diagnostic accuracy study of the multiplex Truenat MTB Ultima/COVID-19 assay for simultaneous detection of Tuberculosis and SARS-CoV2 (COVID-19)

The COVID-19 pandemic led to significantly disrupted tuberculosis case detection and management. Additionally, overlapping symptoms, radiological findings and risk factors make differentiating tuberculosis and COVID-19 disease difficult. We conducted a prospective multicentre diagnostic accuracy study to determine sensitivity, specificity and operational characteristics of the Truenat MTB Ultima/COVID-19 assay, using a combined sputum plus nasopharyngeal swab specimen, in a single multiplex molecular assay. Participants were consenting adults with presumptive tuberculosis enrolled via convenience sampling from Uganda, Peru, South Africa, and India between August 2022 and December 2023. A microbiological reference standard of sputum GeneXpert MTB/RIF Ultra and culture was used for tuberculosis, whereas national RT-PCR was used for COVID-19. Wilsons score method was used to determine the sensitivity and specificity. Of 1,928 participants enrolled, median age was 38 years (IQR 28-50), 359/1928 (18.6%) previously had TB, and 287/1928 (14.9%) were HIV-positive. Overall prevalence of tuberculosis was 24.8% [95% CI 22.9-26.8%]. Prevalence of COVID-19 was 3.8% [3.1-4.8%] overall, and 4.7% [3.1-7.0%] in those with confirmed tuberculosis. Overall sensitivity of Truenat MTB Ultima/COVID-19 for tuberculosis was 79.8% [95% CI 76.0-83.2%]. When comparing paired samples, Truenat MTB Ultima/COVID-19 had a 9.5% [6.5-13.1%] decreased sensitivity against sputum TB culture, compared to GeneXpert Ultra; (82.8% [ 78.9-86.1%] vs 92.4% [89.4-94.5%]). Overall specificity of Truenat MTB Ultima/COVID-19 for tuberculosis was 98.9% [98.2-99.3%]. For COVID-19 detection, sensitivity of Truenat MTB Ultima/COVID-19 was 64.4% [52.9-74.4%], with specificity of 99.2% [98.7-99.5%]. Although optimal diagnostic performance was not demonstrated, the potential and need for rapid development of tests that integrate tuberculosis diagnosis with detection of other relevant respiratory infections is highlighted. The study was registered on ClinicalTrials.gov (NCT05405296).