Abstract Body: Background: Ongoing surveillance of stroke incidence over time by demographic groups is critical to understand trends in disease burden and effective interventions. Our objective was to examine changes in stroke incidence by sex and age over 27 years.

Methods: In a population-based stroke surveillance study covering a 5-county region of southern Ohio and northern Kentucky, hospital cases of stroke were ascertained and adjudicated by trained study physicians during six 1-year periods (07/1993–06/1994, 1999, 2005, 2010, 2015, 2020). Temporal trends in stroke incidence were evaluated by sex, age, and subtype (ischemic (IS), hemorrhagic (ICH), subarachnoid hemorrhage (SAH)). Stroke incidence rates per 100,000 people were calculated using U.S. Census data and age-, race-, and sex-standardized as appropriate. Trends in incidence over time were evaluated using linear regression, weighted with the inverse of the standard error of the estimated incidence rate. Female:male risk ratios (RRs) were reported in each of the study periods for the overall population stratified by age, and the trend over time was evaluated using linear regression using inverse weighting of the standard error.

Results: 11,813 stroke events occurred in total, 56% in females and 20% in Black patients (Table 1). The trend over time for any stroke (IS, ICH, SAH or unknown) was not significant in females (208 [95%CI 195-221] in 1993/4 to 187 [95%CI 176-198] in 2020, per 100,000, p=0.06) or males (251 [95%CI 233-269] in 1993/4 to 220 [95%CI 207-234] in 2020, per 100,000, p=0.13). The decreasing trend in IS was significant in females (p=0.03) but not males (p=0.07). Trend in ICH was not significant in females (p=0.75) or males (p=0.06), and trend in SAH was not significant in either sex (all trend data in Figure 1). For female: male RRs for any stroke, overall (combined age groups) RRs ranged from 0.83 (95%CI 0.75-0.91) in 1993/4 to 0.97 (95%CI 0.88-1.06) in 2010; trend over time was not significant (p=0.82). RRs varied with age (2020 data in Figure 2) with a U-shaped relationship.

Discussion: Over 27 years in a population-based stroke surveillance study, trends over time in any, IS, ICH, and SAH appear to be stabilizing with the only significant decrease seen in females with IS. Though findings suggest that previously reported decreasing incidence rates in stroke appear to be trending upward in 2020, future work is needed to understand the effect of COVID on 2020 rates and to continue surveillance.