Treatment Completion and Associated Factors in Drug-Resistant Tuberculosis, Mbuji-Mayi, Democratic Republic of the Congo: A Retrospective Cohort Study

Purpose: Evidence on treatment completion among patients with drug-resistant tuberculosis (DR-TB) in the Democratic Republic of the Congo is limited. We estimated the treatment completion rate and identified factors associated with completion among patients with rifampicin-resistant/multidrug-resistant tuberculosis (RR/MDR-TB) in Mbuji-Mayi. Patients and Methods: This retrospective cohort included all patients with RR/MDR-TB who initiated treatment between January 2019 and December 2023 in the 10 health zones of Mbuji-Mayi. Treatment completion was defined as a documented completed treatment course without evidence of failure; all other recorded outcomes were classified as non-completion. Variables were classified as baseline or treatment-period variables. Modified Poisson regression with cluster-robust variance at the health-zone level estimated adjusted risk ratios (aRRs). Results: Of 514 patients, 382 (74.3%; 95% CI 70.4– 77.9) completed treatment. Completion ranged from 69.7% to 78.8% by year (p = 0.653) and from 60.4% to 87.5% by health zone (p = 0.041). After adjustment, completion was associated with age ≤ 50 years (aRR 1.21 (1.11– 1.31)), normal nutritional status (aRR 1.30 (1.22– 1.40)) and directly observed treatment (aRR 1.26 (1.16– 1.37)). Among treatment-period variables, negative month-3 culture (aRR 1.36 (1.15– 1.62)), absence of treatment interruption (aRR 1.68 (1.30– 2.17)) and absence of drug stock-out (aRR 1.84 (1.44– 2.34)) were also associated with completion. The age association was driven by patients older than 60 years. Conclusion: About three quarters of patients completed DR-TB treatment, with variation across health zones. Because month-3 culture, treatment interruption and drug stock-outs were recorded during treatment, temporality cannot be established for these associations; prospective studies with complete outcome reporting are needed. Keywords: drug-resistant tuberculosis, treatment completion, directly observed treatment, sputum culture conversion, drug stock-outs, Democratic Republic of the Congo