title: Self-assessed health status, walking speed and mortality in older Mexican-Americans.
abstract: BACKGROUND
  Self-assessed health status (SAHS) and physical performance measures (in particular, walking speed) are strong predictors of health-related events. Nevertheless, the possible interaction between them in predicting major outcomes has not been clearly explored.
  
  
  OBJECTIVE
  The aim of the study is to evaluate the predictive and additive value for mortality of a SAHS measure and a walking speed test.
  
  
  METHODS
  Data are from 2,139 Mexican-Americans aged >or=65 years enrolled in the Hispanic Established Populations for Epidemiologic Studies of the Elderly, and followed for 5.8 years. At the baseline visit, participants were asked to answer to the question 'How is your health in general?' presented as a four-level Likert item (i.e., poor, fair, good, excellent). They were also asked to 'walk down and back as fast as it felt safe and comfortable' along an 8-ft track. Cox proportional hazard models, receiver operating characteristic (ROC) curve, and specificity/sensitivity analyses were performed to evaluate the predictive value of SAHS and walking speed for mortality.
  
  
  RESULTS
  The mean age of the sample was 72.1 years. Participants reporting 'poor' SAHS were more likely to die compared to those with 'excellent' SAHS, even after adjustment for potential confounders (HR 1.52, 95% CI 1.10-2.10). Similar results were obtained for participants with slow walking speed (<0.29 m/s; HR 1.68, 95% CI 1.27-2.24; reference group: walking speed >or=0.81 m/s). A statistically significant, but weak, correlation between SAHS and walking speed was observed (Pearson's r=0.069, p=0.001). No significant differences in areas under curves from ROC analyses were reported for the prediction of mortality when the SAHS and walking speed were tested (alone or in combination). Both tests presented high specificity (>or=80%) for the prediction of mortality.
  
  
  CONCLUSIONS
  SAHS and walking speed are not only significant and independent predictors of mortality in older Mexican-Americans, but also present a similar predictive value. The additive prognostic value of the two measures is limited.
authors.affiliation: Department of Aging and Geriatric Research, University of Florida-Institute on Aging, Gainesville, FL 32611, USA. macesari@gmail.com
authors.forename: Matteo
authors.initials: M
authors.lastname: Cesari
authors.forename: Marco
authors.initials: M
authors.lastname: Pahor
authors.forename: Emanuele
authors.initials: E
authors.lastname: Marzetti
authors.forename: Valentina
authors.initials: V
authors.lastname: Zamboni
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Colloca
authors.forename: Matteo
authors.initials: M
authors.lastname: Tosato
authors.forename: Kushang V
authors.initials: KV
authors.lastname: Patel
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Tovar
authors.forename: Kyriakos
authors.initials: K
authors.lastname: Markides
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D006304:Health Status; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D009026:Mortality; D010809:Physical Fitness; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012372:ROC Curve; D015206:Southwestern United States / Q000453:epidemiology; D011795:Surveys and Questionnaires; D016138:Walking / Q000502:physiology*