title: Improvement in usual gait speed predicts better survival in older adults.
abstract: OBJECTIVE
  To estimate the relationship between 1-year improvement in measures of health and physical function and 8-year survival.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Medicare health maintenance organization and Veterans Affairs primary care programs.
  
  
  METHODS
  Persons aged 65 and older (N=439).
  
  
  METHODS
  Six measures of health and function assessed at baseline and quarterly over 1 year. Participants were classified as improved at 1 year, transiently improved, or never improved for each measure using a priori definitions of meaningful change: gait speed (usual walking pace over 4 m), 0.1 m/s; Short Physical Performance Battery, 1 point; Medical Outcomes Study 36-item Short Form Health Survey physical function, 10 points; EuroQol, 0.1 point; National Health Interview activity of daily living scale, 2 points; and global health change, two levels or reaching the ceiling. Mortality was ascertained from the National Death Index. Covariates included demographics, comorbidity, cognitive function, and hospitalization.
  
  
  RESULTS
  Of the six measures, only improved gait speed was associated with survival. Mortality after 8 years was 31.6%, 41.2%, and 49.3% for those with improved, transiently improved, and never improved gait speed, respectively. The survival benefit for improvement at 1 year persisted after adjustment for covariates (hazard ratio=0.42, 95% confidence interval=0.29-0.61, P<.001) and was consistent across subgroups based on age, sex, ethnicity, initial gait speed, healthcare system, and hospitalization.
  
  
  CONCLUSIONS
  Improvement in usual gait speed predicts a substantial reduction in mortality. Because gait speed is easily measured, clinically interpretable, and potentially modifiable, it may be a useful "vital sign" for older adults. Further research is needed to determine whether interventions to improve gait speed affect survival.
authors.affiliation: Division of Geriatric Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA. hardys@dom.pitt.edu
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hardy
authors.forename: Subashan
authors.initials: S
authors.lastname: Perera
authors.forename: Yazan F
authors.initials: YF
authors.lastname: Roumani
authors.forename: Julie M
authors.initials: JM
authors.lastname: Chandler
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Studenski
mesh_terms: D000203:Activities of Daily Living / Q000145:classification; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005684:Gait; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D009026:Mortality; D010809:Physical Fitness; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013223:Statistics as Topic; D016019:Survival Analysis; D014481:United States; D016138:Walking