Baseline sputum time to detection predicts month two culture conversion and relapse in non-HIV-infected patients.

BACKGROUND: Few biomarkers are available to identify tuberculosis (TB) patients at risk of delayed sputum conversion and relapse. OBJECTIVES: To investigate whether baseline pre-treatment time to detection (TTD) of culture predicted 2-month bacteriological conversion and TB relapse. METHODS: A total of 263 non-HIV-infected smear-positive previously untreated pulmonary TB patients were prospectively followed from diagnosis until treatment outcome after 6 months' treatment and TB recurrence within 24 months. RESULTS: The median TTD was 3 days (range 1-17). Of 211 (80.2%) patients with favourable treatment outcome, 22 (10.4%) had recurrence, while 12 (5.7%) had confirmed relapse. Culture conversion at 2 months was associated in univariate analysis with the presence and number of cavities, extensive parenchymal involvement, male sex, sputum smear grading and TTD. In multiple logistic regression, TTD or smear grading and extensive parenchymal involvement both predicted month 2 conversion. Relapse was predicted by TTD, sex, body mass index, smear grading and number of cavities in univariate analysis, and in multivariate regression by TTD and sputum smear grading. CONCLUSIONS: Baseline TTD and smear grading predicted month 2 culture conversion, relapse and also recurrence. These markers may be useful to identify non-HIV-infected patients at risk of recurrence, and may be relevant in clinical trials.