Association of Beta-2 Microglobulin with Stroke and All-Cause Mortality in Adults Aged ≥40 in U.S.: NHANES III

Background: Stroke is the predominant cause of death worldwide. We aimed to investigate the association of serum beta-2 microglobulin ( $\beta$ 2M) concentrations with risk of stroke and all-cause mortalities in a cohort study.

Methods: Overall, 4914 U.S. adults (mean age = 63.0 years, 44.3% male) were recruited from the National Health and Nutrition Examination Survey (NHANES Ⅲ). During a median follow-up of 19.4 years, 254 stroke deaths and 3415 all-cause deaths were identified by the National Center for Health Statistics. The associations of $\beta$ 2M with stroke and all-cause mortalities were investigated by using weighted Cox proportional hazard regression models.

Results: $\beta$ 2M was positively associated with stroke and all-cause mortality in unadjusted models and multivariable-adjusted models. The multivariable HR (95% CI) for stroke mortality in Q5 VS Q1 of serum $\beta$ 2M concentrations was 3.45 (1.33-8.91; p for trend = 0.001) and that for all-cause mortality was 3.95 (3.05-5.12; p for trend $<$ 0.001). In subgroup analyses, the association of $\beta$ 2M and stroke mortality did not vary by different levels of sociodemographic and general stroke risk factors (p _interaction $>$ 0.05). In addition, the magnitude of positive association between $\beta$ 2M with all-cause mortality did vary by age, ratio of family income to poverty, smoking status, and history of hypertensive (p _interaction $<$ 0.05).

Conclusions: Our findings suggest that support that $\beta$ 2M may be a marker of stroke and all-cause mortality, which provides a new perspective for the study of cerebrovascular health and long-term survival in the future.