title: Appendicular lean mass does not mediate the significant association between vitamin D status and functional outcome in hip-fracture women.
abstract: OBJECTIVE
  To investigate whether muscle mass mediates the significant association between vitamin D status and functional recovery after hip fracture in women.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Rehabilitation hospital in Italy.
  
  
  METHODS
  We investigated white women (N=280) of 305 who were consecutively admitted to a rehabilitation hospital because of their first fracture of the hip.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  To assess muscle mass, we measured appendicular lean mass (aLM) by dual-energy x-ray absorptiometry (DXA), 21.2±6.2 (mean ± SD) days after hip fracture occurrence in the 280 women. On the same day, we assessed serum levels of 25-hydroxyvitamin D and parathyroid hormone (PTH). Ability to function in activities of daily living was evaluated by the Barthel Index both before and after acute inpatient rehabilitation.
  
  
  RESULTS
  After adjustment for 8 confounders, including age, cognitive impairment, pressure ulcers, neurologic impairment, infections, fracture type, Barthel Index score at admission to rehabilitation, and aLM/height(2) (aLM/ht(2)), 25-hydroxyvitamin D levels were significantly associated both with Barthel Index scores after rehabilitation (P=.003) and their changes during rehabilitation (P=.008). Similar results were obtained when the 25-hydroxyvitamin D/PTH ratio was substituted for 25-hydroxyvitamin D levels. Conversely, aLM/ht(2) was not significantly correlated with Barthel Index scores and their changes during rehabilitation. Furthermore, we found no significant associations between either 25-hydroxyvitamin D levels or the 25-hydroxyvitamin D/PTH ratio and aLM/ht(2).
  
  
  CONCLUSIONS
  The significant association between 25-hydroxyvitamin D levels (and 25-hydroxyvitamin D/PTH ratio) and the ability to function in women with hip fractures was not mediated by aLM assessed by DXA.
authors.affiliation: Osteoporosis Research Center, Presidio Sanitario San Camillo, Torino, Italy. Medici@h-sancamillo.to.it
authors.forename: Marco
authors.initials: M
authors.lastname: Di Monaco
authors.forename: Carlotta
authors.initials: C
authors.lastname: Castiglioni
authors.forename: Fulvia
authors.initials: F
authors.lastname: Vallero
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Monaco
authors.forename: Rosa
authors.initials: R
authors.lastname: Tappero
mesh_terms: D015502:Absorptiometry, Photon; D000203:Activities of Daily Living; D000368:Aged; D001823:Body Composition / Q000502:physiology*; D004185:Disability Evaluation; D005121:Extremities; D005260:Female; D006620:Hip Fractures / Q000097:blood / Q000503:physiopathology* / Q000534:rehabilitation*; D006801:Humans; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000502:physiology*; D010281:Parathyroid Hormone / Q000097:blood; D020127:Recovery of Function; D013851:Thinness; D014807:Vitamin D / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D