Hidden in Success: Gendered Patterns of Suboptimal Care Engagement Among TB Patients Who "Successfully" Completed Treatment in South Africa

Background: Adherence to tuberculosis (TB) treatment is key to optimal health outcomes. Programmatic definitions of treatment success may mask heterogeneity in care engagement patterns that increase risk of unfavorable outcomes. Methods: Using patient-level medication refill data, latent-class growth modeling was used to identify longitudinal trajectories of care engagement among participants who programmatically achieved treatment success. Logistic regression was conducted to investigate participant-level characteristics associated with trajectory class membership. Results: Among 548 participants, we identified three trajectories: Class 1 (consistent engagement; 84.1%), Class 2 (suboptimal engagement after 2 months; 7.7%) and Class 3 (suboptimal engagement from initiation; 8.2%). At treatment completion, Classes 1-3 accumulated 9.7 (95% CI: 7.4-11.8), 68.4 (60.4-76.9) and 55.5 (48.1-62.7) missed refill days, respectively. In gender-stratified models, men exhibited all three trajectories (83.1%, 7.4%, and 9.5%, respectively), and accumulated 10.6 [7.8-13.3], 61.0 [50.2-71.3], 53.3 [53.3-71.4] missed refill days, respectively. Women exhibited only Classes 1 and 3 (89.5% and 10.5%, respectively) and accumulated 12.1 [7.8-16.5] and 46.9 [33.3-61.6] missed refill days, respectively. Among men, prior TB (Class 2: aOR 7.44, 2.79-19.8; Class 3: aOR 2.78, 1.07-7.25) and HIV-negative status (Class 3: aOR 2.72, 1.13-6.54) were associated with suboptimal trajectories. Among women, prior TB was associated with suboptimal engagement (aOR 5.22, 1.11-24.44). Conclusion: Programmatic "Treatment Success" obscured suboptimal engagement trajectories. Patient-centered counseling and gender-responsive interventions are needed to address suboptimal engagement across treatment stages. Shorter treatment regimens will unlikely resolve suboptimal engagement, underscoring the importance of regimen forgiveness.