title: Improved self-confidence was a mechanism of action in two geriatric trials evaluating physical interventions.
abstract: OBJECTIVE
  To evaluate the mechanisms of action in two successful geriatric clinical trials that tested multicomponent physical conditioning programs and to determine whether the pathways for overall benefit were through improvement in physical ability and/or self-confidence.
  
  
  METHODS
  PREHAB and DRIVER were conducted by the Yale Pepper Center. PREHAB participants received an individualized program that focused on the impairments present (standardly tailored design); DRIVER participants received the entire intervention (global design). PREHAB enrolled 188 community-living persons, aged 75 years or older, who were physically frail but ambulatory; DRIVER enrolled 178 drivers aged 70 years or older with physical impairments associated with poor driving performance. The primary outcome for PREHAB was a disability score and for DRIVER it was a driving score; potential mediators were measures of physical ability and self-confidence.
  
  
  RESULTS
  In PREHAB, pathways for the intervention were established through improvement in physical ability and self-confidence. In DRIVER, there was some evidence for a pathway through improved driving self-confidence but not through physical ability; however, the intervention effect was largely unexplained.
  
  
  CONCLUSIONS
  Multicomponent physical interventions may operate through psychological mechanisms, and these mechanisms should be anticipated in trial designs so that the component effects can be suitably evaluated.
authors.affiliation: Department of Epidemiology and Public Health, Yale School of Medicine, New Haven, CT, USA. peter.peduzzi@yale.edu
authors.forename: Peter
authors.initials: P
authors.lastname: Peduzzi
authors.forename: Zhenchao
authors.initials: Z
authors.lastname: Guo
authors.forename: Richard A
authors.initials: RA
authors.lastname: Marottoli
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Gill
authors.forename: Katy
authors.initials: K
authors.lastname: Araujo
authors.forename: Heather G
authors.initials: HG
authors.lastname: Allore
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D001334:Automobile Driving / Q000523:psychology / Q000592:standards; D004812:Epidemiologic Methods; D016330:Frail Elderly / Q000523:psychology*; D015577:Geriatric Assessment; D006699:Home Care Services; D006801:Humans; D010809:Physical Fitness; D026741:Physical Therapy Modalities; D012107:Research Design; D012649:Self Concept; D020377:Self Efficacy; D016896:Treatment Outcome