Abstract 11938: Risk Factors for Subarachnoid Hemorrhage
Introduction: Subarachnoid hemorrhage (SAH) is a devastating disease, with a high mortality rate and significant disability among survivors. Its causes are poorly understood.
Hypothesis: We aimed to investigate risk factors for SAH using an adequately powered novel nationwide cohort consortium with uniform collection of clinical outcomes.
Methods: We obtained individual participant data of 949,683 persons (330,334 women) who were between 25 and 90 years old and had no history of SAH at baseline, from 21 population-based cohorts collected during more than 50 years and geographically covering entire Sweden. Outcomes were obtained from the Swedish Hospital Discharge and Causes of Death Registries.
Results: During 13,704,959 person-years of follow up, 2,659 first-ever fatal or non-fatal SAH instances were observed. In Poisson regression models with random effects for the cohort level, referencing the population distribution in Sweden year 2010, we observed an age-standardized incidence rate of 9.0 (95% confidence interval 7.4-10.6)/100,000 person-years in men and 13.8 (11.4-16.2)/100,000 person-years in women; rate ratio (RR) 1.45 (1.32 to 1.61) for women vs. men. The incidence rate increased exponentially with higher age, with a plateau of similar risk between ages 55 and 75. The RR was 8.28 (4.39 to 15.63) for age-group 85-89 vs. 25-29 years. Lower education level was associated with higher risk, RR 1.56 (1.27 to 1.96) for primary education vs. post-secondary education. Smoking was associated with a markedly increased risk, with an interaction between smoking and sex. Smoking conferred a RR of 1.66 (1.49 to 1.85) in men, and 2.63 (2.27 to 3.05) in women (p<0.01 for interaction). Hypertension was associated with a RR of 1.33 (1.22 to 1.45) for SAH. Several other risk factors were investigated.
Conclusions: In this large population-based study, a nearly 50% higher risk of SAH was observed in women than in men. Besides higher age, smoking was the most powerful risk factor for SAH, with a markedly stronger effect in women than in men. Lower education was also linked to higher risk.
Author Disclosures: J. Sundstrom: Consultant/Advisory Board; Modest; Itrim. B. Svennblad: None. M. Söderholm: None. S. Söderberg: Speakers Bureau; Modest; Actelion Ltd (Pulmonary Arterial Hypertension). Consultant/Advisory Board; Modest; Actelion Ltd (Pulmonary Arterial Hypertension). M. Eriksson: None. M. Malfert: None. S. Heller: None. G. Engström: None. B. Wiberg: None.
- © 2016 by American Heart Association, Inc.