IS is a leading cause of death and disability in the US. Contemporary trends in incidence (reflecting primary prevention) and recurrence (reflecting secondary prevention) are not well described but are critical to guide strategies that reduce stroke burden.
We conducted a retrospective cohort study using electronic health record data from an integrated healthcare system in Wisconsin and Illinois. Adults (≥18 years) with an emergency department or inpatient admission for IS (ICD-10) and no prior atrial fibrillation were included. One-year recurrent IS was defined as a hospitalization for a second stroke within 1 year of index discharge (21-day washout period to exclude index stroke re-admissions). Age-adjusted incidence rates/100 person-years (PY) and 1-year recurrence/100 PY were calculated for 2015–2023 in Wisconsin and 2021–2023 in Illinois.
Among 16,503 patients with IS (Wisconsin n=10,246; Illinois n=6,257), mean (±standard deviation) age was 68.5±14.1 years, 51.2% were male, and 68.4% were non-Hispanic White. In Wisconsin (2015−2023), incidence significantly increased from 0.43 to 0.52/100 PY (absolute difference [AD] 0.09, 95% confidence interval [CI] 0.05−0.13). In Illinois (2021–2023), incidence stayed high, remaining at ~0.70/100 PY (AD 0.04, 95% CI 0.01–0.09). One-year IS recurrence showed no notable change: Wisconsin, 15.41/100 PY in 2015 to 17.71/100 PY in 2023 (AD 2.30, 95% CI –1.03−5.63); Illinois, 13.64/100 PY in 2021 to 11.85/100 PY in 2023 (AD 1.79, 95% CI –0.49−4.07).
In Wisconsin, the rising incidence of IS suggests gaps in primary prevention. Stable recurrence indicates treatment and secondary prevention have not worsened, though improvement is needed. In Illinois, incidence and recurrence remain high with no notable change, though data are limited to 3 years. Strategies including risk-factor evaluation are needed to strengthen prevention and management of IS.