Thyroid Autoantibodies Are Associated with a Reduced Prevalence of Frailty in Community-Dwelling Older Women

Abstract

The contribution of autoimmunity to the multisystem dysregulation that characterizes the frailty syndrome in older adults is unknown. The aim of the study was to investigate the relationship between thyroid antibodies and frailty in older women. We conducted a cross-sectional study nested within the Women's Health and Aging Studies I and II. Thyroglobulin antibodies (TgAbs), thyroid peroxidase antibodies (TPOAbs), and antinuclear antibodies were measured in the baseline sera of 641 community-dwelling older women. Frailty was defined using a validated five-component measure. The prevalence of prefrailty and frailty was lower in TgAb-positive than negative older women (37.1 vs. 47.8% and 6.7 vs.11.9%, respectively; P = 0.01 and 0.03). The prevalence of prefrailty, but not frailty, was lower in TPOAb-positive than negative women (38.9 vs. 48.0% and 10.1 vs. 11.3%; P = 0.04 and 0.34). After adjustment for covariates including serum thyroid stimulation hormone concentration and thyroid medication usage in multinomial regression models, TgAb-positive older women had lower odds of prefrailty and frailty compared with TgAb-negative women (odds ratio 0.57 and 0.30; 95% confidence interval 0.34-0.98 and 0.10-0.85, respectively). Similarly, TPOAb-positive older women had lower odds of frailty compared with TPOAb-negative women (odds ratio 0.44; 95% confidence interval 0.20-0.96). These trends were not observed with antinuclear antibodies. Independent of thyroid function status, community-dwelling older women who are seropositive for TgAbs and TPOAbs are less likely to be frail than seronegative women.