Determinants of medication adherence and blood pressure control among hypertensive patients in Hong Kong: a cross-sectional study

Introduction: Despite effective treatments, suboptimal medication adherence substantially hinders blood pressure (BP) control among hypertensive patients. This study aimed to evaluate the determinants of medication adherence and BP control among hypertensive patients in Hong Kong. Methods: A cross-sectional study was conducted. Adult patients aged > 18 years taking at least one type of antihypertensive drugs were recruited from four clinics in Hong Kong. Each patient completed a self-administered questionnaire, including socio-demographic variables and items related to knowledge, illness perception and medication adherence. Medication adherence was measured by the eight-item Morisky Medication Adherence Scale (MMAS-8), with a score > 6 defined as “good adherence”. BP was measured, and optimal control was defined as systolic BP < 140 mm Hg and diastolic BP < 90 mm Hg. Results: Among 2445 patients, 55.1% and 52.5% had optimal medication adherence and BP control, respectively. Binary logistic regression analyses were conducted with optimal medication adherence and BP control, respectively, as the outcome variables. Advanced age (adjusted odds ratio [aOR] 1.012, 95% CI 1.002–1.022, p = 0.014), unemployment (aOR for employed 0.782, 95% CI 0.628–0.975, p = 0.029), and good self-perceived health status (aOR 2.155, 95% CI 1.711–2.714, p < 0.001) were associated with good adherence; whereas being married (aOR 1.265, 95% CI 1.038–1.542, p = 0.020) and having no co-morbidity (aOR for morbidity count 0.713, 95% CI 0.639–0.796, p < 0.001) were associated with optimal BP control. Conclusion: Evidence-based, adherence-enhancing interventions should be targeted on younger subjects; employed patients; and those with poor self-perceived health status. Patients who are single and those with comorbidities should be closely monitored for their BP control