Impact of comorbid diseases and associated factors on tuberculosis treatment outcomes among tuberculosis patients in South West Oromia, Ethiopia: a retrospective cohort study

Comorbid diseases are complex diseases associated with tuberculosis that may affect tuberculosis treatment outcomes and mortality. The impact of comorbid diseases on tuberculosis treatment outcomes and mortality is not well known in Ethiopia. To assess the impact of comorbid diseases and associated factors on tuberculosis treatment outcomes among tuberculosis patients in Southwest Oromia, Ethiopia. A multicenter retrospective cohort study was performed. Information on sociodemographic, clinical conditions, drug-related factors, and treatment outcomes was extracted. The collected data were entered into Epi-Data version 4.6 for data entry and exported to SPSS version 25 (IBM Corp., Armonk, NY, USA) for statistical analysis. Independent t-tests were used for continuous variables and chi-square for categorical variables for comparison of the tuberculosis patients with and without comorbid disease groups. Univariate and multivariate logistic regression were used for outcomes analysis. Statistical significance was determined at a p-value < 0.05 in multivariate logistic regression. Among a total of 1183 tuberculosis patients, females were 825(69.8%), and the mean age of the patients was 40.17 with a standard deviation of ± 16.02. The prevalence of unsuccessful tuberculosis treatment outcomes was 14.29%. Treatment interruption, death, and treatment failure among tuberculosis patients were 1.35%, 7.10%, and 5.83%, respectively. Comorbid diseases were a significant risk factor for unsuccessful tuberculosis treatment outcome (adjusted relative risk (RR) = 3.198, 95% CI 1.755-4.901), P < 0.001). Additionally, age (RR = 1.057, 95% CI 1.036-1.078, p < 0.001), being male (RR = 2.026, 95% CI 1.361-3.016, p = 0.001), living in rural areas (RR = 3.092, 95% CI 2.038-4.691, p < 0.001), and Charlson comorbidity index scores (1, 2, and ≥ 3) were independent predictors of unsuccessful tuberculosis treatment outcome. This study revealed that the prevalence of unsuccessful tuberculosis treatment outcomes was high. Comorbid diseases, Charlson comorbidity index scores (1, 2, and ≥ 3), age, being male, and living in rural areas were predictors for unsuccessful tuberculosis treatment outcome. It is important to implement an integrated management strategy for both tuberculosis and comorbid diseases to reduce the rate of unsuccessful tuberculosis treatment outcomes.