[Personal View] Whom tuberculosis tests detect and why it matters: implications for diagnostic algorithms

Tuberculosis encompasses a spectrum of characteristics—including bacillary burden, clinical severity, and access to care—that are relevant to clinical and epidemiological outcomes and the performance of diagnostic assays. The value of diagnostic assays depends not only on their numerical accuracy, which can vary substantially between populations, but also on which individuals with and without tuberculosis the assays identify. Moreover, detectable features of tuberculosis, such as pathogen burden or host responses, are often correlated, making it difficult to predict the accuracy and impact of diagnostic algorithms from the accuracies of individual component tests.