The Journals of Gerontology Series A: Biological Sciences and Medical Sciences Advance Access published online on February 27, 2009
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, doi:10.1093/gerona/gln047
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White Blood Cell Counts, Insulinlike Growth Factor-1 Levels, and Frailty in Community-Dwelling Older Women
1 Division of Geriatric Medicine and Gerontology and Center on Aging and Health, Johns Hopkins University, Baltimore, Maryland
2 Department of Geriatrics, Mount Sinai School of Medicine, New York
3 Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia
4 Mailman School of Public Health, Columbia University, New York
Address correspondence to Sean X. Leng, MD, PhD, Division of Geriatric Medicine and Gerontology, 5505 Hopkins Bayview Circle, Johns Hopkins School of Medicine, Baltimore, MD 21224. Email: sleng1{at}jhmi.edu
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Abstract |
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Background.: Elevated white blood cell (WBC) counts and decreased insulin-like growth factor-1 (IGF-1) levels are individually associated with frailty in older adults. WBC subpopulations are known to produce IGF-1 and express IGF-1 receptors in vitro. However, in vivo relationships between WBC and IGF-1 and their joint contribution to frailty have not been investigated.
Methods.: Baseline data from 696 community-dwelling older women in the Women’s Health and Aging Study I were included in this cross-sectional analysis. Multivariate linear regression analysis was performed to assess the relationship between WBC counts and IGF-1 levels. Odds ratios (ORs) for frailty were evaluated across tertiles of WBC counts and IGF-1 levels, adjusting for age, race, education, body mass index, and smoking.
Results.: WBC counts correlated with IGF-1 levels (Spearman coefficient: .10, p < .01). Compared with participants in the low WBC and high IGF-1 tertiles (reference group), those in the low WBC and low IGF-1 tertiles had OR of 2.33 for frailty (95% confidence interval [CI]: 1.04–3.65, p < .05), those in the high WBC and high IGF-1 tertiles had OR of 3.86 (95% CI: 1.13–4.07, p < .01), and those in the high WBC and low IGF-1 tertiles had OR of 3.61 (95% CI: 1.64–4.97, p < .01), adjusting for covariates.
Conclusions.: These findings demonstrate in vivo correlation between WBC and IGF-1. They suggest U-shaped joint associations of WBC and IGF-1 with frailty, with the strongest association at adverse levels of both. They also provide a basis for further investigation into the complex immune–endocrine dysregulations in frailty.
Keywords Frailty; WBC; IGF-1
Received: April 7, 2008; Accepted: October 6, 2008