Sputum monitoring during tuberculosis treatment for predicting outcome: systematic review and meta-analysis

Abstract

Summary In new pulmonary tuberculosis (TB) patients, the World Health Organization previously recommended performing sputum smear examination at the end of the second month of therapy and, if positive, to extend the intensive phase. We performed a systematic review and meta-analysis to evaluate the accuracy of a positive sputum smear or culture during treatment for predicting failure or relapse in pulmonary TB. We searched PubMed, EMBASE, and the Cochrane Library for studies published in English through December 2009. We included randomized controlled trials, cohort, and case-control studies of previously untreated pulmonary TB patients who had received a standardized regimen with rifampin in the initial phase. Accuracy results were summarized in forest plots and pooled using a hierarchical regression approach. Fifteen papers met inclusion criteria. The pooled sensitivities for both the 2 month smear (24%, 95% CI 12–42, 6 studies) and culture (40%, 95% CI 25–56, 4 studies) to predict relapse were low. Corresponding specificities (85%, 95% CI 72–90) and (85%, 95% CI 77–91) were higher, but modest. For failure, the 2 month smear (7 studies) had low sensitivity (57%, 95% CI 41–73) and higher, though modest, specificity (81%, 95% CI 72–87). Both sputum smear microscopy and mycobacterial culture during TB treatment have low sensitivity and modest specificity for predicting failure and relapse. Although we pooled a diverse group of patients, the individual studies had similar performance characteristics. Better predictive markers are needed.