Effect of Adherence to Antihypertensive Medication on the Long-Term Outcome After Hemorrhagic Stroke in Korea

Abstract

Hypertension is the single most important risk factor for hemorrhagic stroke, a leading cause of mortality and disability worldwide. Adherence to antihypertensive medication is essential to achieving strict blood pressure control, but poor adherence is common in clinical practice. We evaluated adherence to antihypertensive medication in patients with acute hemorrhagic stroke and its effects on long-term outcome. This was a retrospective cohort study based on a nationwide health insurance claims database in South Korea. We included 1872 hypertensive patients who were admitted with acute hemorrhagic stroke during 2002 to 2013 (1354 cases of intracerebral hemorrhage and 518 cases of subarachnoid hemorrhage). Adherence to antihypertensive medication was calculated using the proportion of days covered by any antihypertensive medication throughout the follow-up period (categorized into poor <40%; intermediate 40%-80%; good >80%) and treated as a time-dependent variable. Primary outcome was defined as a composite of recurrent stroke (hemorrhagic or ischemic), myocardial infarction, or all-cause mortality. Time-dependent Cox proportional hazard regression analyses were performed. During the mean follow-up period of 4.45 years, 634 patients had the primary outcome. The proportion of patients with good adherence to antihypertensive medication was 46.8% at 1 year, 43.2% at 3 years, and 41.7% at 5 years of follow-up. Compared with good adherence, the adjusted hazard ratio (95% confidence interval) for the primary outcome was 1.80 (1.49-2.16) for poor adherence and 1.56 (1.27-1.93) for intermediate adherence.