title: Low health literacy predicts decline in physical function among older adults: findings from the LitCog cohort study.
abstract: BACKGROUND
  Limited health literacy is associated with worse physical function in cross-sectional studies. We aimed to determine if health literacy is a risk factor for decline in physical function among older adults.
  
  
  METHODS
  A longitudinal cohort of 529 community-dwelling American adults aged 55-74 years were recruited from an academic general internal medicine clinic and federally qualified health centres in 2008-2011. Health literacy (Newest Vital Sign), age, gender, race, education, chronic conditions, body mass index, alcohol consumption, smoking status and exercise frequency were included in multivariable analyses. The 10-item PROMIS (Patient-Reported Outcomes Measurement Information System) physical function scale was assessed at baseline and follow-up (mean=3.2 years, SD=0.39).
  
  
  RESULTS
  Nearly half of the sample (48.2%) had either marginal (25.5%) or low health literacy (22.7%). Average physical function at baseline was 83.2 (SD=16.6) of 100, and health literacy was associated with poorer baseline physical function in multivariable analysis (p=0.004). At follow-up, physical function declined to 81.9 (SD=17.3; p=0.006) and 20.5% experienced a meaningful decline (>0.5 SD of baseline score). In multivariable analyses, participants with marginal (OR 2.62; 95%CI 1.38 to 4.95; p=0.003) and low (OR 2.57; 95%CI 1.22 to 5.44; p=0.013) health literacy were more likely to experience meaningful decline in physical function than the adequate health literacy group. Entering cognitive abilities to these models did not substantially attenuate effect sizes. Health literacy attenuated the relationship between black race and decline in physical function by 32.6%.
  
  
  CONCLUSIONS
  Lower health literacy increases the risk of exhibiting faster physical decline over time among older adults. Strategies that reduce literacy disparities should be designed and evaluated.
authors.affiliation: Health Literacy and Learning Program, Division of General Internal Medicine and Geriatrics, Northwestern University, Chicago, Illinois, USA Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Smith
authors.affiliation: Health Literacy and Learning Program, Division of General Internal Medicine and Geriatrics, Northwestern University, Chicago, Illinois, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: O'Conor
authors.affiliation: Health Literacy and Learning Program, Division of General Internal Medicine and Geriatrics, Northwestern University, Chicago, Illinois, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Curtis
authors.affiliation: Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Katie
authors.initials: K
authors.lastname: Waite
authors.affiliation: Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, The University of Edinburgh, Edinburgh, UK.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
authors.affiliation: Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, The University of Edinburgh, Edinburgh, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Paasche-Orlow
authors.affiliation: Health Literacy and Learning Program, Division of General Internal Medicine and Geriatrics, Northwestern University, Chicago, Illinois, USA Department of Learning Sciences, Northwestern University, Evanston, Illinois, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wolf
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D015992:Body Mass Index; D002641:Chicago / Q000453:epidemiology; D002908:Chronic Disease / Q000453:epidemiology*; D000066492:Cognitive Aging / Q000502:physiology; D015897:Comorbidity; D005260:Female; D015438:Health Behavior; D057220:Health Literacy; D054624:Health Status Disparities; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity
keywords: AGEING; Cohort studies; LONGITUDINAL STUDIES; PHYSICAL FUNCTION; PSYCHOLOGY