Abstract P38: Pooled Analysis of Long and Short Term Outcomes After Subarachnoid Hemorrhage - International Stroke Outcomes Study (INSTRUCT)

Abstract

Background: Outcomes after subarachnoid hemorrhage (SAH) have been rarely examined in large cohorts. Methods: This is an extension of the International Stroke Outcomes Study (INSTRUCT) pooling 13 ‘ideal’ stroke incidence studies (n=657 with SAH from 1993-2017, median age 56 years; 46% men). The primary outcomes were mortality and functional outcome (mRS score 3-5). Harmonized study factors included age, sex, behaviors (current smoking, alcohol intake), comorbidities (history of hypertension, ischemic heart disease, atrial fibrillation), stroke severity (e.g. NIHSS score) and year of stroke. In the pooled dataset, we estimated predictors of mortality using Poisson regression, to estimate incidence rate ratio (IRR) at 1 month (11 studies), 1 year (12 studies) and 5 years (7 studies). Generalized equation estimates in the log-binomial family were used to calculate risk ratios (RRs) for predictors of poor functional outcome at 1 month (5 studies) and 1 year (8 studies). Results: Mortality was 33% at 1 month, 43% at 1 year, and 47% at 5 years (Fig 1). Poor functional outcome was 25% at 1 month and 15% at 1 year (Fig 1). In multivariable analysis, age and stroke severity were associated with mortality at all time points, together with current smoking at 1 and 5 years, and history of hypertension at 5 years (Fig 2). Poor functional outcome was predicted by age (RR 1.03; 95% CI 1.01-1.04) at 1 month and by age (RR 1.04; 95% CI 1.00-1.08) and stroke severity (RR 1.94; 95% CI 1.02-2.87) at 1 year. Conclusion: Risk factors that predict SAH incidence including hypertension and smoking make outcomes worse. Better management of older patients and those with severe strokes could improve outcomes after SAH.