ABSTRACT
In particular, urine-based tests aim to detect the mycobacterium lipoarabinomannan antigen, part of the outer cell wall of mycobacteria. It is less invasive to collect urine than sputum samples in clinical settings, with lower infection risk to healthcare workers. A test's epidemiological impact is driven by its sensitivity, or the proportion of true TB cases it can detect. A test's specificity, or the proportion of those without TB that it correctly diagnoses as negative, has no direct bearing on its epidemiological impact, and instead is more relevant for the number of unnecessary TB treatments incurred as a result of false-positive diagnosis. Although a LAM test may correctly diagnose such patients, this diagnosis would be deemed incorrect by a sputum-based microbiological reference standard. For future quantitative analysis, therefore, there is a need for more systematic estimates of specificity that take account of such shortcomings of any given reference standard.
