Effect of Drug Cost-Exemption Policy on Treatment Outcomes in Multidrug-Resistant Tuberculosis Patients in Guangxi Zhuang Autonomous Region, China: A Nested Case–Control Study

Background: The most effective patient support interventions in low- and middle-income countries remain a research gap in World Health Organization consolidated guidelines on tuberculosis. We explored the impact of a partial drug cost-exemption policy (including cycloserine, moxifloxacin, linezolid, and clofazimine) implemented in Guangxi Zhuang Autonomous Region, China, on treatment outcomes among local multidrug-resistant tuberculosis (MDR-TB) patients. Methods: This case–control study enrolled 424 MDR-TB patients receiving anti-TB treatment between 2020 and 2022 in Guangxi Zhuang Autonomous Region. Data on demographics, treatment regimen, drug cost-exemption status, and adverse reactions were extracted from electronic medical records. Multivariable logistic regression analysis was used to identify factors associated with successful treatment outcomes. Results: Among the 424 enrolled MDR-TB patients, 212 (50.0%) had successful treatment outcomes, including 79 cured (18.6%) and 133 treatment completed (31.4%). Unfavorable outcomes were observed in 212 patients (50.0%), comprising 190 lost to follow-up (44.8%), 19 deaths (4.5%), and 3 treatment failures (0.7%). Multivariable analysis revealed that female sex (aOR = 2.99, 95% CI: 1.55– 5.78), absence of adverse drug reactions (aOR = 11.58, 95% CI: 3.81– 35.18), and receiving drug cost-exemption (aOR = 37.47, 95% CI: 10.97– 127.96) were associated with favorable treatment outcomes. Furthermore, receiving an increasing number of exempted drugs was progressively associated with higher treatment success. Compared to one drug exemption, the aOR for successful outcomes was 3.24 (95% CI: 2.16– 4.87) for two-drug cost-exemption and 5.13 (95% CI: 2.73– 9.65) for three-drug cost-exemption. Conclusion: This nested case–control study demonstrates that implementing drug cost-exemption support policy is associated with significantly improved MDR-TB treatment success rates in resource-limited, high-burden settings in China. Keywords: multidrug-resistant tuberculosis, drug cost-exemption, treatment outcomes, nested case-control study