title: Joint impairment and ambulation in the elderly.
abstract: OBJECTIVE
  To test the impact of joint impairment on ambulation in the elderly, using a multivariate model.
  
  
  METHODS
  Cross-sectional observational study (baseline data from an ongoing longitudinal study).
  
  
  METHODS
  Five hundred thirty-two persons over age 60, including continuing care retirement community (CCRC) (n = 222), homebound (n = 63), and ambulatory (n = 247) respondents. Mean age at assessment = 76.6 (SD = 6.6).
  
  
  METHODS
  Independent variables included sociodemographics, physician measures of lower joint impairment, an index of cormorbidities derived from physical examination or chart abstract, self-assessed arthritis pain, depression, and anxiety. The dependent variable, ambulation, was measured as walk-rate, based on the time required to walk 50 feet.
  
  
  RESULTS
  For the total sample, 61% of the subjects were impaired in more than one lower joint group, with almost 50% of the homebound impaired in more than three joint groups. Demographics (particularly age and education) explained much of the variance in walk-rate. After controlling for demographics and membership in the groups purposely sampled (CCRC, homebound, ambulatory), lower joint impairment accounted for an additional 7% of the variance in walk-rate. Total amount of variance explained by the model was 56% (Adjusted R2 = .56). A 3-point change in lower joint impairment score, equivalent to the maximum impairment score for a single joint group, is associated with a 4-second change in the mean time required to walk 50 feet. The knee and lower spine joints contributed most to the impact of the lower joint impairment measure.
  
  
  CONCLUSIONS
  Among the elderly, age and education are strong predictors of performance on a walk-rate test. Independent of demographics and non-musculoskeletal conditions, joint impairment is associated with diminished walking ability in this population.
authors.affiliation: Center for Health Services and Policy Research, Northwestern University, Evanston, IL 60208.
authors.forename: J
authors.initials: J
authors.lastname: Gibbs
authors.forename: S
authors.initials: S
authors.lastname: Hughes
authors.forename: D
authors.initials: D
authors.lastname: Dunlop
authors.forename: P
authors.initials: P
authors.lastname: Edelman
authors.forename: R
authors.initials: R
authors.lastname: Singer
authors.forename: R
authors.initials: R
authors.lastname: Chang
mesh_terms: D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001007:Anxiety / Q000453:epidemiology; D001168:Arthritis / Q000145:classification / Q000453:epidemiology* / Q000503:physiopathology* / Q000523:psychology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003863:Depression / Q000453:epidemiology; D006233:Persons with Disabilities; D004522:Educational Status; D005260:Female; D015577:Geriatric Assessment; D016852:Housing for the Elderly; D006801:Humans; D008297:Male; D015233:Models, Statistical; D015999:Multivariate Analysis; D010146:Pain / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D016138:Walking