title: Heterogeneity in hip fracture patients: age, functional status, and comorbidity.
abstract: OBJECTIVE
  To examine unidentified heterogeneity in hip fracture patients that may predict variation in functional outcomes.
  
  
  METHODS
  Observational, longitudinal, multisite cohort study.
  
  
  METHODS
  Three separate cohorts from five hospitals in the metropolitan New York area and eight hospitals in Baltimore.
  
  
  METHODS
  Two thousand six hundred ninety-two hip fracture patients treated at one of 13 hospitals and followed for 6 months postfracture.
  
  
  METHODS
  A mobility measure with three categories (independent (walks independently or with a device), limited independence (needs human assistance or supervision to walk 150 feet or one block or able only to walk indoors), and unable to walk) was developed for use with all three cohorts. A similar measure was developed for the other activities of daily living (ADLs): bathing, dressing, feeding, and using the toilet. Cluster analysis was used to form homogenous groups of patients based on baseline demographic characteristics, comorbid conditions, and baseline mobility and ADL independence.
  
  
  RESULTS
  Seven homogeneous subgroups were identified based on prefracture age, health, and functional status, with measurably different 6-month functional outcomes. At least 90% of patients could be correctly classified into the seven groups using simple decision rules about age, ADLs, and dementia status at baseline. Dementia was the only comorbid condition that segmented the groups.
  
  
  CONCLUSIONS
  The heterogeneous hip fracture population can be grouped into homogenous patient clusters based on prefracture characteristics. Differentially targeting services and interventions to these subgroups may improve functional status outcomes.
authors.affiliation: Program of Research in Serious Physical and Mental Illness, Bronx VA Medical Center, New York, New York 10468, USA. joan.penrod@mssm.edu
authors.forename: Joan D
authors.initials: JD
authors.lastname: Penrod
authors.forename: Ann
authors.initials: A
authors.lastname: Litke
authors.forename: William G
authors.initials: WG
authors.lastname: Hawkes
authors.forename: Jay
authors.initials: J
authors.lastname: Magaziner
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Koval
authors.forename: John T
authors.initials: JT
authors.lastname: Doucette
authors.forename: Stacey B
authors.initials: SB
authors.lastname: Silberzweig
authors.forename: Albert L
authors.initials: AL
authors.lastname: Siu
mesh_terms: D000203:Activities of Daily Living / Q000145:classification*; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D015331:Cohort Studies; D015897:Comorbidity; D003663:Decision Trees; D004185:Disability Evaluation; D005260:Female; D016330:Frail Elderly / Q000706:statistics & numerical data*; D006620:Hip Fractures / Q000453:epidemiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009518:New York; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D012307:Risk Factors