Risk of recurrent ischemic stroke after non-cardioembolic ischemic stroke in England and Denmark

Abstract Background Recurrent ischemic stroke (IS) can occur following a non-cardioembolic IS (NCIS), despite following secondary prevention guidelines. We quantified recurrent IS risk following discharge from first-ever NCIS in clinical practice. Methods Adult patients with first-ever NCIS were identified in England (January 2012–February 2020) and Denmark (January 2012–December 2021) and followed through March 2021 (England) and August 2022 (Denmark). Primary outcome was recurrent IS (incidence rates IRs per 100 person years at 12 months and over total follow-up). Cumulative hazard per 100 person years with 95% confidence intervals (CIs) was estimated. Stroke severity at index and recurrent IS were compared in Danish patients. Results Overall, 52,419 English and 62,501 Danish patients were included (respective mean follow-ups: 3.0 and 3.9 years). Recurrent IS events totaled 5857 in England, 9489 in Denmark. IRs/100 person years were similar (England: 3.74 95% CI 3.64–3.84; Denmark: 3.87 95% CI 3.79–3.95), and highest in the first year (England: 7.39 95% CI 7.14–7.65; Denmark: 7.96 95% CI 7.73–8.20). Five-year cumulative hazard of recurrent IS was 16.53 (95% CI 16.06–17.01) in England, 18.05 (95% CI 17.64–18.47) in Denmark. Among Danish cases with severity data (n = 5540), versus index strokes, recurrent IS events were more often moderate (13.84% vs 19.01%) or severe (3.57% vs 7.92%). Conclusions Recurrent IS after NCIS was highest in the first year and remained substantial over 5 years. In Denmark, recurrent IS severity was worse than index events. These findings underscore unmet needs for improved secondary stroke prevention.