Treatment Outcomes of Drug-Susceptible Pulmonary Tuberculosis in Older Adults: A 24-Year Retrospective Study

Background/Objectives: Tuberculosis (TB) in older adults represents an increasing clinical challenge, although this population remains underrepresented in clinical studies. We compared outcomes and permanent regimen modification between age groups in adults treated for drug-susceptible pulmonary TB. Methods: This retrospective study included 3621 consecutive adults treated at an Italian referral centre between 2000 and 2023. Patients were stratified as <65 and ≥65 years for the primary analysis; additional analyses used four age groups and continuous age. Logistic regression models were adjusted for sex, WHO region, socio-economic status, clinical setting, and calendar period. Results: There were 3173 patients aged <65 years and 448 aged ≥65 years. Crude treatment success was similar (90.0% vs. 89.3%; p = 0.65), whereas death during treatment was more frequent among older adults (4.7% vs. 0.3%; p < 0.001) and loss to follow-up among younger adults (6.0% vs. 2.0%; p < 0.001). After adjustment, age ≥65 years was associated with lower odds of treatment success (aOR 0.56, 95% CI 0.39–0.81) and higher odds of death (aOR 12.24, 95% CI 4.83–31.00). Compared with patients aged 65–79 years, those aged ≥80 years had lower adjusted odds of success (aOR 0.41, 95% CI 0.22–0.78; Holm-adjusted p = 0.025) and higher odds of death (aOR 4.49, 95% CI 1.78–11.28; Holm-adjusted p = 0.004). Permanent regimen modification did not differ between the two main age groups (3.8% vs. 4.7%; p = 0.34). Conclusions: Increasing age was associated with lower treatment success and higher mortality, particularly among adults aged ≥80 years, supporting closer clinical monitoring in this population.