Abstract P319: Prospective Association Between Beta-2 Microglobulin and the Risk of Ischemic Stroke in Women

Abstract

Introduction: Elevated beta-2 microglobulin (B2M) is associated with total stroke. Previous studies have not examined the association between B2M and ischemic stroke risk or ischemic stroke subtypes. We hypothesized that women with higher B2M levels would be at increased risk of experiencing ischemic stroke events. Methods: We performed a nested case-control study among women enrolled in the Nurses’ Health Study who provided blood samples at baseline (1989-1990) and were free of cardiovascular disease and cancer. We measured B2M levels in 460 ischemic strokes cases which occurred between 1989-2008 confirmed by medical record review and classified as thrombotic or embolic, and in 460 controls matched 1:1 to the cases on age, race, date of blood collection, menopausal status, postmenopausal hormone use, and smoking status. We analyzed the association between B2M and ischemic stroke using multivariable conditional logistic regression conditional on the matching factors and adjusted for physical activity, body mass index, aspirin use, alcohol consumption, log transformed total cholesterol to HDL cholesterol ratio, and history of diabetes, high blood pressure, and coronary heart disease or revascularization. Results: The mean age at baseline was 60.5 years with a median of 9.0 years to stroke event. Median levels of B2M were higher among cases (1.86 mg/L) than controls (1.80 mg/L; p-value for Wilcoxon rank sum test=0.009). Those in the highest B2M quartile had a multivariable adjusted increased risk of ischemic stroke compared to those in the lowest quartile (OR=1.68; 95% CI: 1.08, 2.62) (Table). Other quartiles were not associated with an increased risk of ischemic stroke compared to those in the lowest quartile. The association between B2M and thrombotic ischemic stroke was similar to the overall ischemic stroke results. However, we observed no association between B2M and embolic ischemic stroke risk. Conclusion: High levels of B2M were associated with an increased risk of ischemic strokes of thrombotic origin among women.