Abstract DP306: Evidence of widening racial disparities in stroke recurrence from 2015 to 2020: A population-based study

Background: Stroke recurrence is associated with significant morbidity and is disproportionately experienced by Black individuals, making it a major target for clinical trials and systems of care. We examined whether stroke recurrence and associated disparities declined from 2015 to 2020 in a large, population-based study of stroke. Methods: Using a well-validated approach, we ascertained all incident TIAs and strokes (including ischemic, intracerebral hemorrhage and subarachnoid hemorrhage) in the Greater Cincinnati Northern Kentucky region during calendar years 2015 and 2020. To increase power, index cases were also ascertained in Black individuals for the last 6 months of 2014 and 2019, respectively. Potential cases were identified by ICD codes, abstracted, and adjudicated by physicians. All stroke events (but no TIAs) during 3 years of follow-up were considered recurrence. Recurrence rates in 2015 and 2020 were first compared with cumulative incidence functions, both overall and race-stratified. The two periods were then compared with a Cox proportional hazard model that was adjusted for age, sex, race, and index stroke subtype. Results: There were 8300 index stroke/TIA events across the two study periods, 3816 in 2015 and 4484 in 2020. Demographic and clinical characteristics were similar between years ( Graphic 1 ), except median age (69 in 2020 vs. 70 in 2015, P=0.01), percentage of Black race (30% in 2020 vs. 27% in 2015, P=0.01), and index event type (70% ischemic infarct in 2020 vs. 66% in 2015, P<0.01). The unadjusted 3-year recurrence rate decreased slightly over time ( Graphic 2 ), 14.4% (95% CI 12.7-16.3%) for 2020 vs. 15.4% (95% CI 13.5-17.6%) for 2015. When comparing 2015 and 2020, the overall recurrence rate was similar in both time periods after adjustment for age, sex, race, and index event type ( Graphic 3 , HR 0.92 95% CI 0.82-1.05); however, there was a marginal interaction between Black race and study year (P=0.09). When this interaction term was included, Black individuals had a stable risk of recurrence in both study periods (HR 1.07, 95% CI 0.87-1.32), while non-Black individuals had a lower risk in 2020 (HR 0.85, 95% CI 0.73-0.995). Conclusions: While recurrence rates were stable overall, there was evidence that the risk of stroke recurrence decreased in non-Black individuals while remaining stable in Black individuals. This suggests widening disparities in recurrent stroke and requires further study.