title: Relating wrist accelerometry measures to disability in older adults.
abstract: OBJECTIVE
  This analysis assessed the extent to which: (1) wrist accelerometer measures were associated with difficulty performing specific activities of daily living and instrumental activities of daily living and (2) these measures contributed important information about disability beyond a typical self-reported vigorous activity frequency question.
  
  
  METHODS
  We used data from the National Social Life, Health and Aging Project (NSHAP) accelerometry sub-study (n=738). Activity was assessed using two wrist-accelerometer measures assessed over 3 days (routine activity expressed as mean count/15s epoch during wake time, and immobile time expressed as the proportion of wake time spent immobile), and self-reported average vigorous activity frequency. The association between routine activity, immobile time and difficulty performing fourteen activities of daily living (ADLs) and instrumental activities of daily living (IADLs) plus two summary measures (any ADL or IADL difficulty), was assessed using logistic regression models, with and without controlling for self-reported vigorous activity.
  
  
  RESULTS
  Self-reported activity was mildly correlated with routine activity (r=0.27) and immobile time (r=-0.21). Routine activity, immobile time, and self-reported vigorous activity were significantly associated with twelve, ten, and fourteen disability measures, respectively. After controlling for self-reported activity, significant associations remained between routine activity and eight disabilities, and immobile time and six disabilities.
  
  
  CONCLUSIONS
  Wrist accelerometry measures were associated with many ADL and IADL disabilities among older adults. Wrist acclerometry in older adults may be useful to help assess disability risks and set individualized physical activity targets.
authors.affiliation: University of Chicago, Department of Medicine, Section of Geriatrics and Palliative Medicine, USA. Electronic address: megan.huisingh-scheetz@uchospitals.edu.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Huisingh-Scheetz
authors.affiliation: University of Chicago, Department of Public Health Sciences, University of Chicago, USA.
authors.forename: Masha
authors.initials: M
authors.lastname: Kocherginsky
authors.affiliation: University of Chicago, Department of Medicine, Section of Geriatrics and Palliative Medicine, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Magett
authors.affiliation: University of Chicago, Department of Medicine, Section of Geriatrics and Palliative Medicine, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Rush
authors.affiliation: University of Chicago, Department of Medicine, Section of Geriatrics and Palliative Medicine, USA.
authors.forename: William
authors.initials: W
authors.lastname: Dale
authors.affiliation: University of Chicago, Department of Sociology and NORC, Center on Aging, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Waite
mesh_terms: D061725:Accelerometry; D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D006233:Persons with Disabilities; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D057566:Self Report; D014953:Wrist
keywords: Accelerometry; Disability; Frail older adult; Motor activity; Self report