Statin therapy and stroke risk in patients with hypercholesterolaemia: a population-based longitudinal study using electronic health records in South London

Background We aim to evaluate the impact of statin prescription on stroke risk in patients with hypercholesterolaemia and to assess disparities in statin prescribing. Methods We analysed electronic health records from patients with hypercholesterolaemia, registered in 41 general practices in south London between 2005 and 2021. The cause-specific hazard ratio of statin prescription on stroke, adjusted for patients’ sociodemographic characteristics and stroke risk factors (smoking ever, hypertension, and diabetes), was estimated using a time-varying exposure Cox proportional hazards model stratified by history of heart diseases. The association between statin prescription and patients’ sociodemographic characteristics was evaluated using a logistic regression. Results Of the 849,968 registered patients, 166,124 (19.5%) had records of hypercholesterolaemia. Among them, 33.5% were prescribed statins, 2.6% had a record of stroke, and 50.6% were female, 31.7%, 16.2% and 8.9% had records of hypertension, diabetes and history of heart diseases, respectively. In a Cox model stratified by history of heart diseases, statin prescription was associated with a reduced hazard of stroke (cause-specific hazard ratio: 0.74; 95% confidence interval (CI): 0.68–0.80, p < 0.001), with follow-up administratively censored at 79 years ( n = 161,527; 97.2%). Statins were less likely prescribed to female patients and patients of Black ethnicity (odds ratio: 0.70, 95% CI: 0.68–0.72, p < 0.001 and odds ratio: 0.82, 95% CI: 0.79–0.85, p < 0.001, respectively). Conclusions Statin therapy prescription is associated with reduced stroke risk in patients with hypercholesterolaemia, yet it was under-prescribed to women and patients of Black ethnicity, highlighting avoidable disparities in preventive care.