Association of dynamics in lean and fat mass measures with mortality in frail older women

Objective: The relationship between body composition and mortality in frail older people is unclear. We used dual-x-ray absorptiometry (DXA) data to examine the association between dynamics in whole-body composition and appendicular (4 limbs) and central (trunk) compartments and all-cause mortality in frail older women. Design: Prospective study with up to 19 years of follow up. Setting: Community dwelling older (≥65) women. Participants: 876 frail older participants of the Women’s Health Initiative Observational Study with a single measure of body composition and 581 participants with two measures. Measurements: Frailty was determined using modified Fried’s criteria. All-cause mortality hazard was modeled as a function of static (single-occasion) or dynamic changes (difference between two time points) in body composition using Cox regression. Results: Analyses adjusted for age, ethnicity, income, smoking, cardiovascular disease, diabetes, stroke, number of frailty criteria and whole-body lean mass showed progressively decreased rates of mortality in women with higher appendicular fat mass (FM) (P for trend=0.01), higher trunk FM (P for trend=0.03) and higher whole-body FM (P for trend=0.01). The hazard rate ratio for participants with more than a 5% decline in FM between two time points was 1.91; 1.67 and 1.71 for appendicular, trunk and whole-body compartment respectively as compared to women with relatively stable adiposity (p<0.05 for all). Dynamics of more than 5% in lean mass were not associated with mortality. Conclusion: Low body fat or a pronounced decline in adiposity is associated with increased risks of mortality in frail older women. These results indicate a need to re-evaluate healthy weight in persons with frailty.