Medication Adherence in Drug-Susceptible Tuberculosis Outpatients: A Cross-Sectional Study at Universitas Indonesia Hospital Using Proportion of Days Covered (PDC) Analysis

Drug-sensitive tuberculosis (DSTB) is an infectious disease primarily caused by Mycobacterium tuberculosis without evidence of resistance to Rifampicin and Isoniazid. In 2022, the World Health Organization (WHO) reported the highest number of new TB cases ever recorded, totalling 7.5 million, with Indonesia having the second highest incidence globally, accounting for 10% of the cases. Assessing medication adherence is a crucial aspect of medicines optimization. Understanding factors that influence adherence to anti-TB drugs (ATD) is important for improving treatment outcomes. This research aimed to analyse medication adherence to ATD and its factors at Universitas Indonesia Hospital (UIH). This retrospective cross-sectional study was conducted at UIH assessing data in the medical records of adult DSTB patients over a two-year period (1^st January 2022 – 31^st December 2023). Medication adherence was assessed using the Proportion of Days Covered (PDC) analysis, and the relationships between variables were analysed by Fisher’s Exact Test, followed by multivariate logistic regression analysis to control various factors. The research found that among 103 outpatients with DSTB, 94 (91.3%) patients had high adherence (PDC ≥90%), 8 (7.8%) patients had moderate adherence (PDC 80–89%), and only 1 (0.9%) patient was non-adherent (PDC <80%) to ATD. Fisher’s Exact Test revealed a significant relationship between gender and medication adherence (p = 0.044). Multivariate logistic regression analysis indicated that patients with a Charlson’s Comorbidity Index (CCI) score of 0 were 8.951 times more likely to exhibit high medication adherence compared to those with a higher CCI score (aOR = 8.951; 95% CI 0.842–95.175; p = 0.044). The severity of comorbidities was statistically significant related to medication nonadherence. These findings suggest that adherence to ATD is significantly impacted by comorbidity severity, underscoring the need for targeted educational interventions to improve adherence, particularly among patients with severe comorbidities, especially during the advanced phase of treatment.