title: Obesity influences transitional states of disability in older adults with knee pain.
abstract: OBJECTIVE
  This study employed relatively new statistical methods to understand how many states are needed to describe disability in older adults with knee pain, describe the relative probability of transitioning between states over time, and examine whether obesity influences the probability of transitioning between states.
  
  
  METHODS
  Prospective epidemiologic study of older adults with knee pain.
  
  
  METHODS
  Community.
  
  
  METHODS
  The participants, 245 women and 235 men, were 65 years or older, had chronic knee pain on most days, and had difficulty with at least 1 mobility-related activity caused by knee pain.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The primary instrument, the Pepper Assessment Tool for Disability, evaluated self-reported difficulty with mobility, basic activities of daily living (ADLs), and instrumental activities of daily living (IADLs).
  
  
  RESULTS
  The Hidden Markov Model yielded 6 states reflecting changes in mobility, ADLs, and IADLs. There is evidence that loss in more demanding mobility-related activities such as stair climbing is an early sign for the onset of disability and that functional deficits in the lower extremities are critical to the early loss of ADLs. Overall the trend is for older adults to experience greater progression than regression and for obesity to be important in understanding severe states of disability.
  
  
  CONCLUSIONS
  These data provide a strong rationale for characterizing disability on a continuum and underscore the fluid nature of disability in older adults. As expected, lower-extremity function plays a key role in the disablement process; obesity is also particularly relevant to understanding severe states of disability.
authors.affiliation: Department of Health and Exercise Science, Wake Forest University School of Medicine, Winston-Salem, NC 27109, USA. rejeski@wfu.edu
authors.forename: W Jack
authors.initials: WJ
authors.lastname: Rejeski
authors.forename: Edward H
authors.initials: EH
authors.lastname: Ip
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Marsh
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Michael E
authors.initials: ME
authors.lastname: Miller
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D018771:Arthralgia / Q000150:complications / Q000453:epidemiology / Q000534:rehabilitation*; D015992:Body Mass Index; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007719:Knee Joint; D008297:Male; D008390:Markov Chains; D051346:Mobility Limitation; D009765:Obesity / Q000150:complications*; D015995:Prevalence; D011446:Prospective Studies; D014481:United States / Q000453:epidemiology