When universal coverage is not enough: a mixed methods exploration of tuberculosis medication adherence in Bangkok

Background Tuberculosis remains a pressing public health concern in Thailand, where medication adherence largely determines treatment success and the prevention of drug resistance. This study sought to examine factors influencing anti-tuberculosis medication adherence among patients attending Lerdsin Hospital in Bangkok. Methods We employed a sequential explanatory mixed methods design. The quantitative phase surveyed 100 tuberculosis patients using a questionnaire grounded in the WHO five-dimensional adherence framework. The qualitative phase involved in-depth interviews with 12 patients selected through purposive sampling. Survey data were analysed using descriptive statistics and binary logistic regression; interview transcripts underwent thematic analysis. Results Eighty-seven percent of participants demonstrated good adherence. Logistic regression identified medication-related factors (OR = 0.178, 95% CI: 0.039–0.804, p = 0.025) and healthcare system factors (OR = 0.327, 95% CI: 0.108–0.985, p = 0.047) as significant negative predictors, with the model explaining 81.5% of variance. Five qualitative themes emerged: the protective role of universal health coverage, barriers to access and continuity, economic burden, social and family support, and cultural beliefs. Joint display analysis revealed both convergence and partial discordance—high satisfaction scores coexisted with process-level frustrations voiced during interviews. Conclusion Although Thailand's universal coverage schemes effectively absorb direct treatment costs, adverse drug reactions and indirect expenses persist as formidable obstacles. Strengthening proactive adverse event management, offsetting hidden costs, and screening for social support gaps at treatment initiation may enhance adherence and curb drug resistance.