Factors associated with unsuccessful treatment outcomes among drug-resistant tuberculosis patients in Loreto, Peru, 2015–2023: A retrospective cohort study

In Loreto, Peru, unsuccessful treatment outcomes among patients with drug-resistant tuberculosis (DR-TB) remain high, underscoring the need to identify associated factors in this Amazonian region. This retrospective cohort study included 417 DR-TB cases registered in the national TB system in Loreto between 2015 and 2023. Loss to follow-up, death, and treatment failure were combined into a single composite outcome variable defined as unsuccessful treatment outcome. Bivariate and multivariable logistic regression analyses were performed to estimate associations between sociodemographic, clinical, and programmatic factors and this outcome. Among the 417 cases analyzed, 49.5% had unsuccessful treatment outcomes: 34.1% due to loss to follow-up, 3.6% due to treatment failure, and 11.8% due to death. Loss to follow-up was the main driver of unsuccessful outcomes, suggesting important gaps in continuity of care and adherence support within the regional health system. In bivariate analyses, unsuccessful outcomes were associated with age 18–30 years (OR: 3.7; 95% CI: 1.6–8.5; p = 0.002), TB-HIV coinfection (OR: 2.4; 95% CI: 1.2–4.6; p = 0.012), previous treatment after loss to follow-up (OR: 2.9; 95% CI: 1.6–5.2; p < 0.001), high bacillary load (+++) (OR: 1.9; 95% CI: 1.0–3.5; p = 0.041), alcoholism (OR: 4.6; 95% CI: 1.5–14.1; p = 0.006), and drug addiction (OR: 7.0; 95% CI: 2.0–24.2; p = 0.002). In the multivariable analysis, alcoholism remained independently associated with unsuccessful outcomes (aOR: 4.0; 95% CI: 1.1–14.2; p = 0.029), while individualized treatment was associated with lower odds of unsuccessful outcomes (aOR: 0.4; 95% CI: 0.1–0.9; p = 0.023). Unsuccessful treatment outcomes among DR-TB patients in Loreto were mainly driven by loss to follow-up, highlighting persistent gaps in treatment continuity and adherence support. Programmatic priorities should include decentralized access to drug-susceptibility testing, community-based adherence strategies, and integrated screening and management of alcohol use within DR-TB care.