title: Association between baseline frailty and driving status over time: a secondary analysis of The National Health and Aging Trends Study.
abstract: BACKGROUND
  Continued automobile driving is important for the wellbeing and independence of older adults. Frailty has been associated with a variety of negative health outcomes, but studies are lacking on the potential association between frailty and driving status. The present study uses data from The National Health and Aging Trends Study (NHATS) to assess if the presence of frailty is associated with being a current non-driver.
  
  
  METHODS
  NHATS is a nationally representative cohort study of Medicare beneficiaries (aged ≥65) that have been followed since 2011. We examined frailty status at baseline (Fried's frailty phenotype) and driving status over 4 years (from 2011 to 2014) excluding never drivers at baseline. Multivariable Poisson regression was used to obtain incidence rate ratios, adjusting for covariates and clustering. To account for the repeated measures in the data collection, generalized estimating equations (GEE) were employed.
  
  
  RESULTS
  A significant association between baseline frailty and driving status was observed at all four time points. At T4, frail participants at baseline had an incidence rate for becoming a current non-driver 1.80 times (or an 80% increase) that of non-frail participants at baseline (adjusted 95% confidence interval (CI) 1.56-2.07).
  
  
  CONCLUSIONS
  Frailty was associated with an increased rate of being a current non-driver. Based on this association, we posit that screening for and intervening on frailty may help certain older adults who are at risk for becoming a current non-driver to remain on the road longer.
authors.affiliation: Department of Epidemiology, Columbia University Mailman School of Public Health, 722 West 168th Street, New York, NY, 10032, USA.
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Bond
authors.affiliation: Department of Epidemiology, Columbia University Mailman School of Public Health, 722 West 168th Street, New York, NY, 10032, USA.
authors.forename: Laura L
authors.initials: LL
authors.lastname: Durbin
authors.affiliation: Department of Epidemiology, Columbia University Mailman School of Public Health, 722 West 168th Street, New York, NY, 10032, USA.
authors.forename: Jodi A
authors.initials: JA
authors.lastname: Cisewski
authors.affiliation: Department of Biostatistics, Columbia University Mailman School of Public Health, New York, NY, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Qian
authors.affiliation: Division of Gerontology, Department of Epidemiology & Public Health, University of Maryland School of Medicine, Howard Hall Suite 200, 660 West Redwood Street, Baltimore, MD, 21201, USA.
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.affiliation: Department of Health Policy and Management, Johns Hopkins University, Bloomberg School of Public Health, 624 North Broadway, Baltimore, MD, 21205, USA.
authors.forename: Judith D
authors.initials: JD
authors.lastname: Kasper
authors.affiliation: Department of Epidemiology, Columbia University Mailman School of Public Health, 722 West 168th Street, New York, NY, 10032, USA. tjm2141@cumc.columbia.edu.
authors.forename: Thelma J
authors.initials: TJ
authors.lastname: Mielenz
keywords: Driving; Epidemiology; Frailty; Measurement; Older adults