Abstract A010: Temporal Trends in the Incidence and Case Fatality Rates of Stroke in the Young: A Population-Based Study

Introduction: While declining overall, stroke-related mortality is rising in the young. We sought to better characterize this trend by examining stroke incidence, case fatality rates, and risk factors among young individuals in a large population-based study of stroke from 1993 to 2020. Methods: In a 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 one-year periods (07/1993-06/1994, 1999, 2005, 2010, 2015, and 2020). Young individuals were defined as ages 20 to 54 years old. Incidence rates were generated using United States Census data standardized to the 2010 population, and 95% confidence intervals were calculated assuming a Poisson distribution. Temporal trends were examined using linear regression. With data from the national death index, 30-day case fatality rates were generated. Trends over time were evaluated with logistic regression, and adjusted for age, race, and sex. Results: There were 2,076 first-ever strokes among young individuals across all study periods. Young individuals with stroke were more likely to have documented hypertension, diabetes, atrial fibrillation, illicit drug use, and marijuana use in recent years (P<0.001). They were more likely to undergo MRI as part of the diagnostic evaluation over time (P<0.001). The incidence rate of stroke among young individuals increased over time (33.88 cases/100,000 person-years in 1993/4, to 63.73 cases/100,000 person-years in 2020, trend P=0.03). Over the same time period, the incidence rate in older individuals declined (618.64 cases/100,000 person-years in 1993/4, to 450.61 cases/100,000 person-years in 2020, trend P=0.01). Examining stroke subtypes, the rise in incidence was primarily driven by an increase in ischemic stroke (trend p=0.02), without statistically significant trends in hemorrhagic stroke. There was a modest decline in the 30-day case fatality rate over time only in young individuals (11.7% in 1993/4, to 9.4% in 2020, trend P=0.0014). Discussion: Stroke incidence is rising in young adults, predominantly due to ischemic strokes. Meanwhile, stroke incidence is declining in older adults. The incidence trend in young stroke coincides with an increase in both traditional risk factors and substance use, though more detailed documentation could be a factor. Further research is needed to understand these worrisome trends for stroke in the young.