Association between statin use and post-ischemic stroke epilepsy among older adults: A nested case-control study

Our primary objective was to estimate the association between post-stroke statin use and post-stroke epilepsy (PSE) and assess whether sex modifies this association. Our second objective was to assess whether statin characteristics and other risk factors affect the risk of PSE overall and within groups defined by sex. We conducted a population-based nested case-control study, using linked health administrative data and including residents older than 65 of Ontario, Canada treated for an ischemic stroke between April 1, 2007, and March 31, 2017. Patients who developed epilepsy were matched with up to 10 controls on age, sex, and month. Multivariable conditional logistic regression models were used to estimate the adjusted odds ratios for PSE associated with post-stroke statin use and potential risk factors. We included 1009 patients with epilepsy and 6522 matched controls. Statin use was not associated with the risk of epilepsy in the entire cohort or in the sex-stratified analysis (IRR = 1.17; 95 % CI 0.95-1.43), and sex did not significantly modify the association (p-value=0.08). Statin characteristics did not affect the risk of epilepsy in the entire cohort; however, we observed an increased risk of PSE associated with the use of atorvastatin among females in the sex-stratified analyses (IRR = 1.26; 95 % CI 1.02-1.56). Although the risk of epilepsy did not significantly differ between statin users and non-users in the entire cohort or within groups defined by sex, atorvastatin was associated with an increased risk of PSE compared to statin non-users among women and should be further explored.