Association between schizophrenia and adherence to medications for secondary stroke prevention

Background — Schizophrenia is associated with an increased risk of stroke and under-treatment of vascular risk factors, but less is known about adherence to medications for secondary stroke prevention. We sought to understand current rates of adherence to secondary stroke prevention therapies among elderly ischemic stroke survivors with and without schizophrenia.

Methods — In a population-based cohort study, we used administrative databases to identify all patients aged ≥65 years who were hospitalized with ischemic stroke in the province of Ontario, Canada, between 2004 and 2018, and a validated algorithm to identify those with schizophrenia. Among patients who filled a prescription for antihypertensive, lipid-lowering, or anticoagulant medications within 3 months and were alive 1 year after discharge, we compared the proportion with low adherence (defined as an annual proportion of days covered of <0.4) in those with and without schizophrenia. We used multivariable logistic regression to estimate the association between schizophrenia and low adherence adjusting for age, sex, comorbid conditions, area of residence, and socioeconomic status.

Results — Of the 55 842 patients included, the mean age was 79.5 years, 53.3% were female, and 1.0% had schizophrenia. Among those who survived to 1 year after discharge, individuals with schizophrenia were more likely than those without to have low adherence to antihypertensive (28.0% versus 18.8%; adjusted odds ratio, 1.60 [95% CI, 1.28-2.01]), lipid-lowering (38.6% versus 29.8%; adjusted odds ratio, 1.60 [95% CI, 1.31-1.96]), or anticoagulant medications (41.1% versus 32.0%; adjusted odds ratio, 1.61 [95% CI, 1.00-2.58]), even after adjustment for age, sex, comorbid illness, rurality, and neighborhood income quintile.

Conclusions — Schizophrenia is associated with poor adherence to medications for secondary stroke prevention. Future work should focus on developing individual- and system-level interventions to improve vascular risk factor management in this population.