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.
Materails 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.

Keywords
Tuberculosis, death, directly observed treatment-short course, revised National Tuberculosis Control Programme