Diagnostic accuracy and inter-lot precision of the FujiLAM II point-of-care assay to detect tuberculosis in stored urine specimens from people living with HIV.

UNLABELLED: The Fujifilm SILVAMP TB LAM II (FujiLAM II) assay is a lateral flow assay that detects TB from urine specimens. This updated version of the assay has been redesigned to address inter-lot variability issues of the original FujiLAM assay. We evaluated the diagnostic accuracy and inter-lot variability of the FujiLAM II assay on biobanked urine specimens collected from inpatients and outpatients living with HIV in two prospective studies conducted at hospitals in Cameroon. Diagnostic performance was evaluated against microbiological reference standards and compared to the Determine TB LAM Ag (AlereLAM) test and smear microscopy. From January to March 2025, urine specimens from 798 people with HIV were tested and analyzed, including 128 (16%) with microbiologically confirmed TB. Against a microbiological reference standard including two sputum liquid cultures and sputum, urine, and blood Xpert Ultra, the sensitivity of the FujiLAM II was 49% (58/119, 95% CI 40%-58%) as compared to 35% (42/119, 95% CI 27%-44%) on the AlereLAM, and the specificity of FujiLAM II was 96% (621/650, 95% CI 94%-97%) as compared to 92% (601/650, 95% CI 90%-94%) on the AlereLAM. Among a subset of 161 participants with any TB result positive, positivity across four manufacturing lots ranged from 37% (60/161, 95% CI 30%-45%) to 42% (67/161, 95% CI 34%-49%), with no significant difference across lots (Cochran's Q = 4.2, P = 0.2). These results suggest the FujiLAM II assay has the potential to improve TB diagnosis in some populations, as compared to the only currently available LAM test.

IMPORTANCE

Many people with TB are never diagnosed with and treated for the disease. While sputum-based tests for TB based on molecular diagnostics are highly sensitive, there are many barriers to access due to the high cost and infrastructure requirements of these tests. Accurate, point-of-care tests that can be conducted in peripheral settings without equipment and on non-sputum specimens have the potential to greatly increase access to TB testing and close this gap in care. The Fujifilm SILVAMP TB LAM II test is a new urine-based lateral flow test for TB. Our results show that this test is more sensitive to detect TB in people living with HIV than the only currently recommended urine point-of-care TB test and that the test has consistent performance across lots.