Statin Adherence Reduces Recurrent Stroke Risk

Study Questions:

Do statins reduce the risk of recurrent ischemic stroke caused by atrial fibrillation (AF)?

Methods:

This is a retrospective cohort study of ischemic stroke patients from Kaiser Permanente Northern California, an integrated healthcare system. Data were obtained from the electronic medical records for 2008-2012 for patients prescribed a statin within 90 days of discharge. Prescription days covered was used to measure statin adherence, and patients were stratified by diagnosis or absence of AF.

Results:

A total of 6,116 patients with an ischemic stroke were identified, and 1,446 had AF. The mean prescription days covered for statin use was 85 for the cohort, and patients were stratified by <85 prescription days covered (n = 1,853) and ≥85 prescription days covered (n = 4,263). At baseline, higher prescription days covered was associated with older age, diagnosis of AF, coronary artery disease, diabetes mellitus, and heart failure. Statin adherence was lower in Black and Hispanic patients. Low-density lipoprotein (LDL) cholesterol was used as a surrogate to validate the statin prescription days covered measure. As expected, a higher prescription days covered for statin use was associated with a greater likelihood of achieving a 30 mg/dL reduction in LDL cholesterol. A multivariable survival model, after controlling for gender, race/ethnicity, comorbidities, and hospital center, found that higher statin adherence was associated with a 41% relative risk reduction (hazard ratio [HR] 0.59; 95% confidence interval [CI], 0.43-0.81; p = 0.001) in ischemic stroke risk in patients with AF and a 22% relative risk reduction (HR 0.78; 95% CI, 0.63-0.97; p = 0.023) in ischemic stroke risk in patients without AF. Furthermore, similar reductions in ischemic stroke risk (HR 0.61; 95% CI, 0.41-9.90; p = 0.012; n = 1,010) were observed in a subgroup of patients with AF who were receiving warfarin, after adjusting for time in therapeutic range.

Conclusions:

Statin adherence is associated with a reduced risk of recurrent ischemic stroke irrespective of whether the stroke was associated with AF. Additionally, the observed benefit with statin adherence was even greater in patients with AF compared with those without AF. There was no association between statin adherence and increased risk of hemorrhagic stroke.

Perspective:

These findings suggest that statins reduce recurrent ischemic stroke risk regardless of AF status and may be even more effective in patients with AF. Limitations of this study include its retrospective design and an imperfect, but acceptable, prescription days covered measurement of medication adherence. Clinicians should encourage patients with a history of ischemic stroke to adhere to statin therapy.

Clinical Topics: Arrhythmias and Clinical EP, Dyslipidemia, Heart Failure and Cardiomyopathies, Atrial Fibrillation/Supraventricular Arrhythmias, Lipid Metabolism, Nonstatins, Novel Agents, Statins, Acute Heart Failure

Keywords: Atrial Fibrillation, Cholesterol, LDL, Coronary Artery Disease, Diabetes Mellitus, Heart Failure, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Medication Adherence, Stroke


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