title: Weight change, body composition, and risk of mobility disability and mortality in older adults: a population-based cohort study.
abstract: OBJECTIVE
  To examine associations between weight change, body composition, risk of mobility disability, and mortality in older adults.
  
  
  METHODS
  Prospective, longitudinal, population-based cohort.
  
  
  METHODS
  The Health, Aging, and Body Composition Study.
  
  
  METHODS
  Women (n = 1,044) and men (n = 931) aged 70 to 79.
  
  
  METHODS
  Weight and lean and fat mass from dual-energy X-ray absorptiometry measured annually over 5 years. Weight was defined as stable (n = 664, reference), loss (n = 662), gain (n = 321), or cycling (gain and loss, n = 328) using change of 5% from year to year or from Year 1 to 6. Mobility disability (two consecutive reports of difficulty walking one-quarter mile or climbing 10 steps) and mortality were determined for 8 years after the weight change period. Associations were analyzed using Cox proportional hazards regression adjusted for covariates.
  
  
  RESULTS
  During follow-up, 313 women and 375 men developed mobility disability, and 322 women and 378 men died. There was no risk of mobility disability or mortality with weight gain. Weight loss (hazard ratio (HR) = 1.88, 95% confidence interval (CI) = 1.40-2.53) and weight cycling (HR = 1.59, 95% CI = 1.11-2.29) were associated with mobility disability in women, and weight loss was associated with mobility disability in men (HR = 1.30, 95% CI = 1.01-1.69). Weight loss and weight cycling were associated with mortality risk in women (weight loss: HR = 1.47, 95% CI = 1.07-2.01; weight cycling: HR = 1.62, 95% CI = 1.15-2.30) and in men (weight loss: HR = 1.41, 95% CI = 1.09-1.83; weight cycling: HR = 1.50, 95% CI = 1.08-2.08). Adjustment for lean and fat mass and change in lean and fat mass from Year 1 to 6 attenuated the relationships between weight loss and mobility disability in men and between weight loss and mortality in men and women.
  
  
  CONCLUSIONS
  Weight cycling and weight loss predict impending mobility disability and mortality in old age, underscoring the prognostic importance of weight history.
authors.affiliation: Laboratory of Epidemiology, and Population Sciences, Intramural Research Program, National Institute on Aging, Bethesda, MD.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Murphy
authors.affiliation: Center for Pain Research on Impact, Measurement & Effectiveness, Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, WA.
authors.forename: Kushang V
authors.initials: KV
authors.lastname: Patel
authors.affiliation: Sticht Center on Aging, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.affiliation: Sticht Center on Aging, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC.
authors.forename: Denise K
authors.initials: DK
authors.lastname: Houston
authors.affiliation: Center for Aging and Population Health, Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.affiliation: CAPHRI School for Public Health and Primary Care, Department of Social Medicine, Maastricht University, Maastricht, the Netherlands.
authors.forename: Annemarie
authors.initials: A
authors.lastname: Koster
authors.affiliation: Translational Gerontology Branch, National Institute on Aging, Baltimore, MD.
authors.forename: Eleanor M
authors.initials: EM
authors.lastname: Simonsick
authors.affiliation: Department of Preventive Medicine, University of Tennessee, Health Science Center, Memphis, TN.
authors.forename: Frances A
authors.initials: FA
authors.lastname: Tylvasky
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Cawthon
authors.affiliation: Laboratory of Epidemiology, and Population Sciences, Intramural Research Program, National Institute on Aging, Bethesda, MD.
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D015502:Absorptiometry, Photon; D000203:Activities of Daily Living; D000368:Aged; D000886:Anthropometry; D001823:Body Composition; D004185:Disability Evaluation; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D051346:Mobility Limitation; D009026:Mortality / Q000639:trends*; D011446:Prospective Studies; D012306:Risk; D014481:United States; D015431:Weight Loss
keywords: aging; body composition; muscle loss; obesity; physical function