Predictors of unsuccessful tuberculosis treatment outcome in Bhutan: A retrospective study using comprehensive national tuberculosis surveillance data

Despite the high burden of tuberculosis in Bhutan, data on treatment outcomes are limited. Using a national TB dataset from 2018 to 2021, provided by the National Tuberculosis Reference Laboratory, we conducted a retrospective cohort study to assess treatment outcomes and explore factors associated with unsuccessful TB outcomes. Of the 3,619 patients who received TB treatment, 3,330 had a recorded treatment outcome. Among these, 96.2% (n = 3,202) had a successful outcome (44.4% (n = 1,480) were cured and 51.7% (n = 1,722) completed treatment), and 3.8% (n = 128) had an unsuccessful outcome (2.8% (n = 93) died, 0.7% (n = 23) experienced treatment failure, and 0.4% (n = 12) were lost to follow-up). Multivariable logistic regression showed patients older than 60 years of age (aOR 4.3; 95% CI 2.09-10.0; p-value < 0.001), diagnosed in 2019 (aOR 1.7; 95% CI 1.03–2.86; p-value 0.041), 2021 (aOR 1.74; 95% CI 1.03–2.97; p-value 0.038), and pulmonary TB (aOR 2.69; 95% CI 1.76–4.27; p-value < 0.001) were more likely to have an unsuccessful treatment outcome. The proportion of successful TB treatment exceeded the global target rate of 90%, with a low rate of unsuccessful outcomes. Patients with pulmonary TB and elderly patients require active follow-up to ensure their treatment success increases. In-depth studies need to be conducted to understand the circumstances leading to the treatment failures and death.