Association between statin adherence and the risk of stroke among South Korean adults with hyperlipidemia

Abstract

Background and aims: The effectiveness of statins commonly used to prevent stroke may depend on adherence to treatment. We examined the association between statin adherence and stroke risk among South Korean adults with hyperlipidemia.

Methods and results: The data of 128,052 and 129,390 participants with hyperlipidemia for the purpose of studying the risks of ischemic and hemorrhagic stroke, respectively, were collected from the Korean National Health Insurance Service-National Sample Cohort between 2002 and 2013. Participants were divided into groups according to statin adherence, calculated as the proportion of days covered (PDC; poor, moderate, good). The risk of ischemic and hemorrhagic stroke were analyzed using a Cox proportional hazards model. Individuals with poor PDC exhibited higher risks of ischemic and hemorrhagic stroke than those with good PDC (ischemic stroke: hazard ratio [HR] = 1.09, 95% confidence interval [CI] = 1.03-1.15, hemorrhagic stroke: HR = 1.37, 95% CI = 1.22-1.54). Women with poor PDC were at higher risk of ischemic stroke than those with good PDC (HR = 1.17, 95% CI = 1.09-1.26), while men with poor PDC exhibited a higher risk of hemorrhagic stroke than those with good PDC (HR = 1.55, 95% CI = 1.27-1.90). Individuals with disabilities who had poor PDC were at higher risk of ischemic stroke than those with good PDC (HR = 1.55, 95% CI = 1.24-1.93).

Conclusions: We detected a significant association between statin adherence and ischemic and hemorrhagic stroke risk. Therefore, hyperlipidemia patients should adhere to statin treatment; such interventions are required to reduce the stroke risk.

Keywords: Hemorrhagic stroke; Hyperlipidemia; Ischemic stroke; Proportion of days covered; Statin adherence; Usual provider continuity index.