title: The association between body mass index, weight loss and physical function in the year following a hip fracture.
abstract: OBJECTIVE
  To determine whether body mass index (BMI) at the time of hospitalization or weight change in the period immediately following hospitalization predict physical function in the year after hip fracture.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Two hospitals in Baltimore, Maryland.
  
  
  METHODS
  Female hip fracture patients age 65 years or older (N=136 for BMI analysis, N=41 for analysis of weight change).
  
  
  METHODS
  Body mass index was calculated based on weight and height from the medical chart. Weight change was based on DXA scans at 3 and 10 days post fracture. Physical function was assessed at 2, 6 and 12 months following fracture using the lower extremity gain scale (LEGS), walking speed and grip strength.
  
  
  RESULTS
  LEGS score and walking speed did not differ across BMI tertiles. However, grip strength differed significantly across BMI tertiles (p=0.029), with underweight women having lower grip strength than normal weight women at all time points. Women experiencing the most weight loss (>4.8%) had significantly lower LEGS scores at all time points, slower walking speed at 6 months, and weaker grip strength at 12 months post-fracture relative to women with more modest weight loss. In adjusted models, overall differences in function and functional change across all time points were not significant. However, at 12 months post fracture,women with the most weight loss had an average grip strength 7.0 kg lower than women with modest weight loss (p=0.030).
  
  
  CONCLUSIONS
  Adjustment for confounders accounts for much of the relationships between BMI and function and weight change and function in the year after fracture. However, weight loss is associated with weakness during hip fracture recovery. Weight loss during and immediately after hospitalization appears to identify women at risk of poor function and may represent an important target for future interventions.
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, 624 N. Broadway Room 698, Baltimore, MD 21205, USA. lsemanic@jhsph.edu
authors.forename: L
authors.initials: L
authors.lastname: Reider
authors.forename: W
authors.initials: W
authors.lastname: Hawkes
authors.forename: J R
authors.initials: JR
authors.lastname: Hebel
authors.forename: C
authors.initials: C
authors.lastname: D'Adamo
authors.forename: J
authors.initials: J
authors.lastname: Magaziner
authors.forename: R
authors.initials: R
authors.lastname: Miller
authors.forename: D
authors.initials: D
authors.lastname: Orwig
authors.forename: D E
authors.initials: DE
authors.lastname: Alley
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D015142:Baltimore; D015992:Body Mass Index; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006620:Hip Fractures / Q000503:physiopathology*; D006760:Hospitalization; D006801:Humans; D011446:Prospective Studies; D016138:Walking / Q000502:physiology; D015431:Weight Loss