title: Transition to sarcopenia and determinants of transitions in older adults: a population-based study.
abstract: BACKGROUND
  Diagnostic criteria for sarcopenia from appendicular lean mass (ALM), strength, and performance have been proposed, but little is known regarding the progression of sarcopenia. We examined the time course of sarcopenia and determinants of transitioning toward and away from sarcopenia.
  
  
  METHODS
  ALM, gait speed, and grip strength were assessed seven times over 9 years in 2,928 initially well-functioning adults aged 70-79. Low ALM was defined as less than 7.95 kg/m(2) (men) or less than 6.24 kg/m(2) (women), low performance as gait speed less than 1.0 m/s, low strength as grip strength less than 30 kg (men) or less than 20 kg (women). Presarcopenia was defined as low ALM and sarcopenia as low ALM with low performance or low strength. Hidden Markov modeling was used to characterize states of ALM, strength, and performance and model transitions leading to sarcopenia and death. Determinants of transitioning toward and away from sarcopenia were examined with logistic regression.
  
  
  RESULTS
  Initially, 54% of participants had normal ALM, strength, and performance; 21% had presarcopenia; 5% had sarcopenia; and 20% had intermediate characteristics. Of participants with normal ALM, strength, and performance, 1% transitioned to presarcopenia and none transitioned to sarcopenia. The greatest transition to sarcopenia (7%) was in presarcopenic individuals. Low-functioning and sarcopenia states were more likely to lead to death (12% and 13%). Higher body mass index (p < .001) and pain (p = .05) predicted transition toward sarcopenia, whereas moderate activity predicted transition from presarcopenia to more normal states (p = .02).
  
  
  CONCLUSIONS
  Pain, physical activity, and body mass index, potentially modifiable factors, are determinants of transitions. Promotion of health approaching old age is important as few individuals transition away from their initial state.
authors.affiliation: Laboratory of Epidemiology and Population Sciences, Intramural Research Program, National Institute on Aging, Bethesda, Maryland. Rachel.murphy@nih.gov.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Murphy
authors.affiliation: Department of Biostatistical Sciences, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Ip
authors.affiliation: Department of Biostatistical Sciences, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, Center for Aging and Population Health, University of Pittsburgh, Pennsylvania.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Boudreau
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Cawthon
authors.affiliation: Department of Epidemiology, Center for Aging and Population Health, University of Pittsburgh, Pennsylvania.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.affiliation: Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis.
authors.forename: Frances A
authors.initials: FA
authors.lastname: Tylavsky
authors.affiliation: Department of Health Sciences, VU University and the EMGO Institute, Amsterdam, The Netherlands. Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Visser
authors.affiliation: Department of Medicine, University of Pittsburgh, Pennsylvania.
authors.forename: Bret H
authors.initials: BH
authors.lastname: Goodpaster
authors.affiliation: Laboratory of Epidemiology and Population Sciences, Intramural Research Program, National Institute on Aging, Bethesda, Maryland.
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D015502:Absorptiometry, Photon; D000367:Age Factors; D000368:Aged; D000375:Aging; D015992:Body Mass Index; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D055948:Sarcopenia / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D012737:Sex Factors; D014057:Tomography, X-Ray Computed
keywords: Aging; Epidemiology.; Muscle; Physical function; Sarcopenia