Survival analysis and risk factors for death in tuberculosis patients on directly observed treatment-short course.

BACKGROUND Tuberculosis is a disease with a high case fatality of 4.65%. OBJECTIVES To describe the survival pattern of patients on Directly Observed Treatment-Short course (DOTS) according to categories, age and sex of patients. SETTINGS Tuberculosis unit (TU) at District Tuberculosis Centre (DTC), Yavatmal, India. DESIGN Retrospective cohort study. MATERIALS AND METHODS Data of patients registered for DOTS in the year 2004 were collected from the tuberculosis register. STATISTICAL ANALYSIS Kaplan Meier plots and log rank tests to assess the survival pattern. Cox proportional hazards model for multivariate analysis. RESULTS A total of 716 patients were registered at the TU. The survival rates by the end of the intensive phase were 96%, 93% and 99% in categories I, II and III of DOTS, respectively. The cumulative survival rates were 93%, 88% and 96% in the three DOTS categories, respectively. There was a significant difference in the survival curves amongst the three DOTS categories (log rank statistic= 7.26, d.f..= 2, P=0 0.02) and amongst the different age groups [log rank statistic= 8.78, d.f.= 3, P= 0.012). There was no difference in the survival curves of male and female patients (log rank statistic= 0.05, d.f.= 1, P= 0.80) and according to type of disease (log rank statistic= 5.63, d.f.= 2, P= 0.05). On Cox proportional hazard analysis, age groups of 40 to 60 years [adjusted hazard ratio= 7.81 (1.002-60.87)] and above 60 years [adjusted hazard ratio= 21.54 (2.57-180.32)] were identified as significant risk factors for death. CONCLUSIONS Age above 40 years is a significant risk factor for death in patients of tuberculosis. There was a significant difference in survival curves of the three DOTS categories and age groups.