Predicting the outcome of therapy for pulmonary tuberculosis

Patients vary considerably in their response to treatment of pulmonary tube rculosis. Although several studies have Indicated that adverse outcomes are more likely in those patients with delayed sputum sterilization, few tools are available to identify those patients prospectively. In this study, mul tivariate models were developed to predict the response to therapy in a pro spectively recruited cohort of 42 HIV-uninfected subjects with drug-sensiti ve tuberculosis, the cohort included 2 subjects whose initial response was followed by drug-sensitive relapse. The total duration of culture positivit y was best predicted by a model that included sputum M. tuberculosis antige n 85 concentration on Day 14 of therapy, days-to-positive in BACTEC on Day 30, and the baseline radiographic extent of disease (R = 0.63). A model in which quantitative AFB microscopy replaced BACTEC also performed adequately (R = 0.58). Both models predicted delayed clearance of bacilli in both rel apses (> 85th percentile of all subjects) using information collected durin g the first month of therapy. Stratification of patients according to antic ipated response to therapy may allow TB treatment to be individualized, pot entially offering superior outcomes and greater efficiency in resource util ization, and aiding in the conduct of clinical trials.