Mortality and associated risk factors in a cohort of tuberculosis patients treated under DOTS programme in Addis Ababa, Ethiopia

BACKGROUND: Tuberculosis (TB) is the leading cause of mortality among infectious diseases worldwide. Ninty five percent of TB cases and 98% of deaths due to TB occur in developing countries. Globally, the mortality rate has declined with the introduction of effective anti TB chemotherapy. Nevertheless, some patients with active TB still die while on treatment for their disease. In Ethiopia, little is known on survival and risk factors for mortality among a cohort of TB patients. The objective of the study is to determine the magnitude and identify risk factors associated with time to death among TB patients treated under DOTS programme in Addis Ababa, Ethiopia. METHODS: This is a retrospective cohort study. Data was obtained by assessing medical records of TB patients registered from June 2004 to July 2009 G.C and treated under the DOTS strategy in three randomly selected health centers. A step-wise multivariable Cox's regression model and Kaplan- Meier curves were used to model the outcome of interest. Mortality was used as an outcome measure. Person-years of observation (PYO) were calculated from the date of starting anti-TB treatment to date of outcome and was calculated as the number of deaths/100 PYO. Statistical analysis SPSS version 16 was used for data analysis and results were reported significant whenever P-value was less than 5%. RESULTS: From a total of 6,450 registered TB patients 236(3.7%) were died. More than 75% death occurred within eight month of treatment initiation. The mean and median times of survival starting from the date of treatment initiation were 7.2 and 7.9 months, respectively. Comparison of survival curves using Kaplan Meier curves method with log-rank test showed that the survival status was significantly different between patient categories as well as across treatment centers (P < 0.05). The death rate of pulmonary positive, pulmonary negative and extra pulmonary TB patients were 2.7%, 3.6%, and 4.3%, respectively. Body weight at initiation of anti-TB treatment (<35 kg), patient category, year of enrollment and treatment center were independent predictors for time to death. CONCLUSIONS: Most of the patients were died at the end of treatment period. This underlines the need for devising a mechanism of standardizing the existing DOTS programme and nutritional support for underweight patients for better clinical and treatment outcome.