Prospective association between β₂-microglobulin levels and ischemic stroke risk among women

To determine whether elevated β₂-microglobulin (B2M) levels were associated with an increased risk of incident ischemic stroke events among women.

We performed a nested case-control study among women enrolled in the Nurses' Health Study who provided blood samples between 1989 and 1990 and were free of prior stroke and cancer. We measured B2M levels in 473 ischemic strokes cases confirmed by medical record review and in 473 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 to adjust for traditional stroke risk factors.

Median levels of B2M were higher among cases (1.86 mg/L) than controls (1.80 mg/L, p = 0.009, Wilcoxon rank-sum test). Women in the highest B2M quartile had a multivariable-adjusted increased risk of ischemic stroke compared to those in the lowest quartile (odds ratio [OR] 1.56, 95% confidence interval [CI] 1.02-2.39). Results were similar when restricted to those without evidence of chronic kidney disease (estimated glomerular filtration rate ≥60 mL·min^-1·1.73 m^-2) (OR 1.49, 95% CI 1.08-2.06). In an exploratory analysis, the association between B2M and thrombotic stroke was similar to the overall ischemic stroke results, but no association was observed for embolic stroke risk.

High levels of B2M were associated with an increased risk of ischemic stroke among women.