Abstract P468: Time Trends in Severity of Incident Ischemic Stroke in the Atherosclerosis Risk in Communities Study From 1987 to 2018

Background: Stroke severity at hospital admission is the most important clinical predictor of short- and long-term functional outcome and mortality after stroke. Decreases in stroke severity over the last two decades have been reported in some countries; however, data on stroke severity from large prospective cohort studies in the US are not available for recent years. We studied trends in stroke severity of incident ischemic stroke from 1987 to 2018 in the prospective Atherosclerosis Risk in Communities (ARIC) study. Methods: Severity of stroke on admission was determined through review of ARIC hospital charts for incident ischemic strokes using the National Institutes of Health Stroke Scale (NIHSS). Events with inadequate information for NIHSS score determination were excluded (n=209). Severity was categorized as minor, NIHSS≤5; mild, 6-10; moderate, 11-15; and severe, ≥16. Mean NIHSS scores by year were presented by age group (Figure) and trends in NIHSS score from 1987 to 2018 were studied with linear regression model. Changes in the proportion of minor stroke compared to more severe stroke (NIHSS>5) were assessed using logistic regression. Multivariable models included age at stroke, sex, race-center, and baseline education level, hypertension, BMI, diabetes and smoking status as covariates. Results: Among 15,661 participants (age 45-64) free of stroke at baseline (1987-89), 1,036 incident stroke cases with severity scores (NIHSS: 638 [61.6%] minor, 222 [21.4%] mild, 88 [8.5%] moderate and 88 [8.5%] severe) were included. Mean age (SD) at incident stroke was 69.5 (9.9) years, 55.2% women and 26.8% Black. For each 1-year calendar time, the adjusted estimate for the continuous NIHSS score was -0.026 (SE=0.040), p=0.5109, and the adjusted OR (95% CI) for NIHSS≤5 compared to NIHSS>5 was 0.99 (0.97, 1.01). Conclusion: Among participants with incident ischemic stroke in the prospective ARIC study, no clear decrease in severity of stroke was observed from 1987 to 2018.