Time to death and its associated factors among tuberculosis patients undergoing directly observed therapy at Butajira General Hospital: using accelerated failure time model

Abstract

Introduction: Tuberculosis (TB) remains a significant public health challenge, especially in resource-limited settings like Ethiopia, where the incidence is estimated at 151 cases per 100,000 population. Delays in diagnosis and treatment contribute substantially to TB-related morbidity and mortality. This study aimed to assess the time to death and identify key risk factors influencing mortality among TB patients receiving directly observed therapy (DOT) at Butajira General Hospital using a parametric survival approach. Methods: A retrospective cohort study was conducted among TB patients treated at Butajira General Hospital between September 2019 and August 2023. Survival analysis techniques including the Kaplan-Meier estimator, stratified Cox proportional hazards model, and the Accelerated Failure Time (AFT) model were employed to estimate survival time and identify factors associated with mortality. Results: Among 571 TB patients included in the study, 99 (17.3%) died during the follow-up period. The Weibull AFT model revealed that male sex (Φ = 0.75, 95% CI: 0.60–0.94, p = 0.015), age over 45 years (Φ = 0.70, 95% CI: 0.50–0.95, p = 0.030), HIV co-infection (Φ = 0.50, 95% CI: 0.35–0.72, p < 0.001), smoking (Φ = 0.60, 95% CI: 0.45–0.80, p < 0.001), multidrug-resistant TB, and working outside healthcare facilities (Φ = 0.70, 95% CI: 0.50–0.98, p = 0.040) were associated with accelerated time to death. In contrast, larger family size fewer than three members (Φ = 1.70, 95% CI: 1.20–2.42, p = 0.004) and more than three members (Φ = 2.50, 95% CI: 1.75–3.60, p = 0.001) as well as extrapulmonary TB (Φ = 1.80, 95% CI: 1.30–2.50, p = 0.001), smear-negative pulmonary TB (Φ = 1.60, 95% CI: 1.20–2.20, p = 0.005), and baseline weight over 35 kg (Φ = 1.90, 95% CI: 1.40–2.60, p < 0.001) were associated with longer survival time. Conclusion: This study identified several significant predictors of TB-related mortality. Male sex, older age, HIV co-infection, smoking, multidrug-resistant TB (MDR-TB), and employment outside healthcare settings were associated with accelerated time to death. In contrast, better nutritional status, larger family support, and non-smear-positive TB types were linked to longer survival. The TB/HIV co-infection rate observed in this cohort exceeded the national average, highlighting the need for strengthened and integrated TB/HIV care. These findings can guide healthcare strategies, emphasizing the need for targeted interventions for high-risk groups and improving social support and healthcare access to enhance patient outcomes in TB management.