Background To investigate the time to initial sputum culture conversion (SCC) and its predictors among multidrug-resistant tuberculosis (MDR-TB) patients in Hangzhou, China.Methods A retrospective cohort study was conducted among patients initiating treatment for MDR-TB from 2011-2015 in Hangzhou, China. Time to initial SCC was analyzed using the Kaplan-Meier method, and Cox proportional hazards regression was used to identify predictors of SCC.Results Among 384 patients enrolled with MDR-TB, 359 (93.5%) successfully achieved initial SCC after a median of 85 days (inter-quartile range, 40-112 days). A higher rate of SCC was observed in participants with successful treatment outcomes than those with poor treatment outcomes (P<0.01). Multivariate analysis showed that age 25-64 years (adjusted odds ratio [AOR], 0.7; 95% confidence interval [CI], 0.5-0.9; P<0.01), age ≥65 years (AOR, 0.5; 95%CI, 0.3-0.8; P<0.01) and household registration in Hangzhou (AOR, 1.3; 95%CI, 1.0-1.5; P<0.05) were found to be associated with SCC.Conclusions Although high SCC and treatment success rates were observed among MDR-TB patients in Hangzhou, the prolonged duration to initial SCC underscores the importance of emphasizing measures for infection control. A new policy of shifting outpatient treatment to inpatient treatment in China may reduce the risk of transmission from patients in the time window prior to SCC.

Background: So far, there are few studies that have investigated the risk of incident multidrug-resistant tuberculosis (MDR-TB) among individuals with previous tuberculosis history (PTBH), let alone developed a nomogram so as to comprehensively estimate an individualized risk of incident MDR-TB in this population. The present study was to construct a comprehensive nomogram for providing simple and precise personalized prediction of incident MDR-TB risk among individuals with PTBH.Methods: A matched case−control study (1: 2 ratios) was performed between 2005 and 2018 in Hangzhou City, China. A multivariable Cox proportional hazard regression was used to evaluate independent predictors of incident MDR-TB in individuals with PTBH. A comprehensive nomogram was developed based on the multivariable Cox model.Results: Overall, 1, 836 participants were included in this study. We developed a simple-to-use nomogram for predicting the individualized risk of incident MDR-TB by using the parameters of age < 60 years, a history of direct contact, passive mode of TB case finding, human immunodeficiency virus infection, re-treated TB history, unsuccessful treatment, 3HRZES/6HRE, duration of pulmonary cavities, and duration of positive sputum culture in individuals with PTBH. The concordance index of this nomogram was 0.833 [95% confidence interval (CI): 0.807-0.859] and 0.871 (95% CI 0.773-0.969) for the training and validation sets, respectively, which indicated adequate discriminatory power. The calibration curves for the risk of incident MDR-TB showed an optimal agreement between nomogram prediction and actual observation in the training and validation sets, respectively. The high sensitivity and specificity of nomogram was indicated by using a receiver operating characteristic curve analysis.Conclusions: We developed and validated a novel nomogram for predicting and preventing the risk of incident MDR-TB in individuals with PTBH. Through this clinic tool, TB control executives could more precisely monitor, estimate and intervene the risk of incident MDR-TB among individual PTB patients.