title: Association of long-distance corridor walk performance with mortality, cardiovascular disease, mobility limitation, and disability.
abstract: BACKGROUND
  Aerobic fitness, an important predictor of cardiovascular disease and mortality, is difficult to assess by maximal exercise testing in older adults. Extended walking tests have been examined as outcome predictors in medically ill populations but not in community-dwelling older adults.
  
  
  OBJECTIVE
  To determine whether an extended walking test predicts poor outcomes in older adults.
  
  
  METHODS
  Observational cohort study enrolling 3075 community-dwelling adults aged 70 to 79 years living in Pittsburgh, Pa, or Memphis, Tenn. Of those participating in the Health, Aging, and Body Composition Study, 1584 (52%) were women and 1281 (42%) were black. Participants enrolled from March 1997 to April 1998. Ability to complete the long-distance corridor walk and total performance time was assessed at the baseline examination.
  
  
  METHODS
  Total mortality, incident cardiovascular disease, incident mobility limitation, and mobility disability were ascertained after a mean (SD) of 4.9 (0.9) years.
  
  
  RESULTS
  Among patients eligible to exercise, 351 died, 308 had episodes of incident cardiovascular disease, 1116 had occurrences of mobility limitation, and 509 had occurrences of mobility disability. Inability to complete walking 400 m tended to be associated with a higher risk of mortality and incident cardiovascular disease and, after accounting for potential confounders, was associated with incident mobility limitation (212.6 vs 79.1 events/1000 person-years; adjusted hazard ratio [HR], 1.86; 95% confidence interval [CI], 1.58-2.18; P<.001) and mobility disability (85.2 vs 28.8 events/1000 person-years; adjusted HR, 1.95; 95% CI, 1.56-2.44; P<.001). Of those who completed 400 m, each additional minute of performance time was associated with an adjusted HR of 1.29 (95% CI, 1.12-1.48) for mortality, 1.20 (95% CI, 1.01-1.42) for incident cardiovascular disease, 1.52 (95% CI, 1.41-1.63) for mobility limitation, and 1.52 (95% CI, 1.37-1.70) for disability after adjustment for demographics, health behaviors, clinical and subclinical disease, and cardiovascular disease risk factors. Findings were consistent in both men and women and blacks and whites. Among participants who completed the test and after adjusting for potential confounders, those in the poorest quartile of functional capacity (walk time >362 seconds) had a higher risk of death than those in the best quartile (walk time <290 seconds; adjusted HR, 3.23; 95% CI, 2.11-4.94; P<.001).
  
  
  CONCLUSIONS
  Older adults in the community who reported no difficulty walking had a wide range of performance on this extended walking test. Ability to do the test and performance were important prognostic factors for total mortality, cardiovascular disease, mobility limitation, and mobility disability in persons in their eighth decade.
authors: Department of Epidemiology, Physical Therapy, University of Pittsburgh, Pittsburgh, Pa 15213, USA. newmana@edc.pitt.edu
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