Association between non-adherence to statins and hospitalization for cardiovascular disease and all-cause mortality in a national cohort

Abstract

Objectives: This study evaluates the effect of adherence to statins on hospitalization for cardiovascular disease and all-cause mortality in South Korea. Methods: We performed a national cohort study on 423,786 individuals using the Korean National Health Insurance Claims Database. The cohort was composed of individuals who were aged between 18 and 84 years, who were newly treated with a statin, and who were followed from 2005 to 2009. Adherence to statin use, determined using the medication possession ratio (MPR) and associations between adherence to statin and health outcomes, was evaluated using Cox's proportional hazards regression analysis. Results: Of the study subjects, 41.9% were male, 7.4% were beneficiaries of a tax-financed medical aid program (MAP), 1.5% had prior cardiovascular disease (CVD), 13.0% had diabetes, and 27.5% had hypertension. Nonadherence to statin use was associated with an increased risk of cardiovascular hospitalization (HR 2.18, 95% CI: 2.02 - 2.35) and all-cause mortality (HR = 1.75, CI: 1.66 - 1.84). As the age of the study group increased, non-adherence was more strongly associated with the risk of hospitalization for CVD. In addition, the risk of hospitalization for CVD was relatively high in patients who were male, older or MAP beneficiaries, and who had hypertension, diabetes, and high Charlson's comorbidity index. Conclusions: This study supports the view that non-adherence to statin use is associated with an elevated risk of hospitalization for cardiovascular disease and all-cause mortality.