Factors influencing antihypertensive medication compliance in Taiwan: a nationwide population-based study

Background: Poor medication compliance with antihypertensive drugs may have a significant impact on clinical outcomes, hospitalisation and healthcare expenditure. This study aims to assess medication compliance and its underlying factors in patients receiving antihypertensive drugs in Taiwan. Methods: This retrospective population-based study was based on data from Taiwan's Longitudinal Health Insurance Database (LHID). All patients (n = 78,558) were aged 30 years or more and had received at least one antihypertensive prescription between January 2004 and December 2007. We used the medication possession ratio (MPR) as an index to measure the level of medication compliance. Results: Approximately 53% of the patients had high compliance with antihypertensive medication. Factors that were positively associated with medication compliance included patients being aged 30―44 years, higher comorbidity scores (odds ratio (OR): 1.18; 95% confidence interval (CI): 1.08―1.28), the same prescribing physician being visited and a single-drug therapy being prescribed. Female sex (OR: 0.92; 95% CI: 0.89―0.95) and higher socioeconomic status (OR: 0.91; 95% CI: 0.86―0.96) were negatively associated with drug compliance. In addition, high-compliance patients were less likely to be treated at medical centres, corporations (OR: 0.89; 95% CI: 0.84―0.93) or rural (OR: 0.88; 95% CI: 0.83―0.94) institutions. Conclusion: Several patient- and institution-related factors may influence medication compliance. Therefore, for optimal outcomes, patients' awareness of the need for compliance with antihypertensive therapy must be enhanced, and effective intervention strategies should be developed.