Risk factors for treatment failure of drug-resistant pulmonary tuberculosis: results from a two-decade data analysis.

Background: Drug-resistant tuberculosis (DR-TB) remains a major public health challenge worldwide, particularly in Eastern Europe, where high disease burden and complex treatment regimens contribute to suboptimal outcomes. Lithuania has historically reported high rates of pulmonary DR-TB; however, data on long-term treatment outcomes and their determinants over extended periods are limited. This study evaluated long-term treatment outcomes among adults with pulmonary DR-TB in Lithuania over a 22-year period and assessed associations between treatment outcomes, individual risk factors, and temporal trends. Methods: A retrospective cohort analysis was conducted using data from the National Tuberculosis Information System for 2000-2021. The study included 5,761 adults with DR-TB, categorized into three periods: Period I (2000-2007), Period II (2008-2015), and Period III (2016-2021). Treatment outcomes were classified as successful (treatment completion with recovery) or unsuccessful [treatment failure, progression to chronic TB, death before completion, or transition from multidrug-resistant tuberculosis (MDR-TB) to extensively drug-resistant tuberculosis (XDR-TB)]. Associations between outcomes and risk factors such as smoking, alcohol and substance use, comorbidities, and sociodemographic variables were examined using multivariate analysis. Results: Treatment success rates increased steadily across periods (66.2%, 68.5%, and 79.5%), while mortality rates declined (30.7%, 29.5%, and 20.1%). Non-lethal treatment failure rates decreased markedly (3.0%, 2.0%, and 0.3%). Treatment failure was significantly associated with low body mass index, male gender, unemployment, homelessness, tobacco and alcohol use, substance abuse, and comorbidities including cancer, cardiovascular and chronic lung disease, diabetes mellitus, human immunodeficiency virus (HIV) infection, and renal failure. Conclusions: Treatment outcomes of DR-TB in Lithuania have shown improvement over a 22-year period. Successful treatment outcomes were strongly influenced by a combination of clinical, behavioral, and socioeconomic factors, underscoring the complexity of DR-TB management. The relative importance of these components may vary for each individual patient. Incorporating multifaceted strategies, such as psychological support, social assistance (including access to food and shelter), and employment opportunities, into the national DR-TB control framework could enhance health system responsiveness and reduce inequities in care.