Inequalities in medication adherence to statin treatment after stroke: A nationwide observational study

Introduction The objective was to investigate differences in adherence to statins after stroke based on age, sex, socioeconomic status and country of birth. Patients and methods Patients with ischemic stroke in 2009–2010 were included from the Swedish stroke register. Adherence to statin treatment was measured over two years as proportion of days covered with 80% as cut-off for adherence. Income, education, and country of birth were obtained from official registers. Factors associated with adherence were controlled for in multivariable logistic regression. Results Of 15,192 included patients, 73.9% had an adherence rate ≥80%. The oldest (85+ years) and youngest (18–54 years) had the lowest adherence, and a smaller proportion of women were adherent (odds ratio (OR) 0.84; 95% confidence interval (CI) 0.77–0.92). Adherence was less common in patients born in Nordic countries (OR 0.82; 95% CI (0.68–0.97), Europe (OR 0.78; 95% CI 0.65–0.93), and in non-European countries (OR 0.65; 95% CI 0.50–0.84) compared to Sweden-born. Patients with university education were to a lower extent adherent compared to patients with primary school education (OR 0.81; 95% CI 0.72–0.91). There was no association between adherence and income. Discussion The study was based on individual level real-life data with national coverage. Adherence was estimated from data on filled prescriptions, but filled prescription does not mean that drugs are used as intended. Conclusion Adherence to statin treatment over two years was suboptimal, and adherence was less common among women, patients born outside of Sweden and patients with university education.