title: Longitudinal associations between self-rated health and performance-based physical function in a population-based cohort of older adults.
abstract: BACKGROUND
  Although self-rated health (SRH) and performance-based physical function (PPF) are both strong predictors of mortality, little research has investigated the relationships between them. The objective of this study was to evaluate longitudinal, bi-directional associations between SRH and PPF.
  
  
  METHODS
  We evaluated longitudinal associations between SRH and PPF in 3,610 adults aged 65-89 followed for an average of 4.8 (standard deviation [SD]: 4.4) years between 1994 and July 2011 in the Adult Changes in Thought study, a population-based cohort in the Seattle area. SRH was assessed with a single-item question in the ACT study. Participants were asked at each evaluation to rate their health as "excellent", "very good", "good", "fair", or "poor" in response to the question "In general, how would you rate your health at this time". PPF scores (ranging from 0-16, with higher indicating better performance) included walking speed, chair rises, grip strength, and balance.
  
  
  RESULTS
  At the baseline visit, participants averaged 74.5 (SD: 5.8) years of age and 2,115 (58.6%) were female. In multivariable linear mixed models, PPF declined with age, with more rapid decreases associated with very good, good, and fair (vs. excellent) baseline SRH. Adjusted annual change in PPF was -0.17 points (95% confidence interval [CI]: -0.19, -0.15) for individuals with excellent baseline SRH and -0.21 points (95% CI: -0.22, -0.19) for participants with fair SRH. In multivariable generalized linear mixed models, lower baseline PPF quartiles were associated with lower odds of excellent/very good/good SRH at age 75, however, differences between baseline PPF quartiles diminished with age.
  
  
  CONCLUSIONS
  These results suggest that less than excellent SRH predicts decline in physical functioning, however, poor physical functioning may not predict change in SRH in a reciprocal fashion. SRH provides a simple assessment tool for identifying individuals at increased risk for decline in physical function.
authors.affiliation: Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington, United States of America.
authors.forename: Willa D
authors.initials: WD
authors.lastname: Brenowitz
authors.affiliation: Group Health Research Institute, Seattle, Washington, United States of America; Department of Biostatistics, University of Washington School of Public Health, Seattle, Washington, United States of America.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Hubbard
authors.affiliation: Department of Medicine, Division of General Internal Medicine, University of Washington, Seattle, Washington, United States of America.
authors.forename: Paul K
authors.initials: PK
authors.lastname: Crane
authors.affiliation: School of Pharmacy, University of Washington, Seattle, Washington, United States of America.
authors.forename: Shelly L
authors.initials: SL
authors.lastname: Gray
authors.affiliation: University of Haifa, Mount Carmel, Haifa, Israel.
authors.forename: Oleg
authors.initials: O
authors.lastname: Zaslavsky
authors.affiliation: Group Health Research Institute, Seattle, Washington, United States of America; Department of Medicine, Division of General Internal Medicine, University of Washington, Seattle, Washington, United States of America.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Larson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D010809:Physical Fitness; D012647:Self-Assessment; D014861:Washington