Factors affecting time to sputum culture conversion and treatment outcome of patients with multidrug-resistant tuberculosis in China

Background: Few prospective cohort studies, none in China, have investigated the relationship between treatment outcomes of multidrug-resistant tuberculosis (MDR-TB) patients and sputum culture conversion. Factors affecting the time of the culture conversion throughout the whole course of the treatment have rarely been investigated. Methods: This study was performed in four cities in Jiangsu province, China. MDR-TB patients were consecutively enrolled between December 2011 and March 2014. Rates of sputum culture conversion were calculated and Cox proportional-hazards model was performed. Factors contributing to sputum culture conversion were investigated. Results: In all, 139 MDR-TB patients with treatment outcomes were enrolled. Median time to culture conversion among those who converted was 91.5 days (interquartile range, 34.0-110.8 days). After multivariable analysis, smoking (HR = 0.44; 95% CI: 0.23-0.83), drinking (HR = 0.41; 95% CI: 0.21-0.81), ofloxacin resistance (HR = 0.43; 95% CI: 0.24-0.76) and sputum smear grade > 1 (HR = 0.51; 95% CI: 0.31-0.83) were less likely to have culture conversion. Conclusions: MDR-TB patients who smoke, drink, have ofloxacin resistance, or a high smear grade are less likely to respond to treatment and should be meticulously followed up.