Associations of neutrophil and monocyte counts with frailty in community-dwelling disabled older women: results from the Women's Health and Aging Studies I.

Frailty is an important geriatric syndrome that predicts disability and mortality. Substantial evidence suggests that inflammation marked by elevated IL-6 levels and total white blood cell (WBC) counts contribute to this syndrome. However, the relationships of WBC subpopulations, the important inflammatory and immune cells, with frailty have not been investigated. To address this important question, we conducted cross-sectional polytomous logistic regression analyses evaluating associations between baseline WBC differential counts and prevalent frailty (defined by the validated Fried's criteria) of 558 disabled women aged 65-101 years and 548 women aged 70-79 living in the community, both from the Women's Health and Aging Studies. The results showed that high neutrophil and monocyte counts were associated with frailty in disabled older women, albeit these associations did not reach statistical significance in women aged 70-79, adjusting for age, race, education, body mass index, smoking, and antibiotic use. In addition, the identified associations were independent of IL-6. No significant associations of lymphocyte, eosinophil, or basophil counts with frailty were observed. These findings provide initial insight into potential roles of neutrophils and monocytes in the pathogenesis of frailty and a basis for further investigation into their function and regulation in frail older women.