title: Inpatient rehabilitation volume and functional outcomes in stroke, lower extremity fracture, and lower extremity joint replacement.
abstract: BACKGROUND
  It is unclear if volume-outcome relationships exist in inpatient rehabilitation.
  
  
  OBJECTIVE
  Assess associations between facility volumes and 2 patient-centered outcomes in the 3 most common diagnostic groups in inpatient rehabilitation.
  
  
  METHODS
  We used hierarchical linear and generalized linear models to analyze administrative assessment data from patients receiving inpatient rehabilitation services for stroke (n=202,423), lower extremity fracture (n=132,194), or lower extremity joint replacement (n=148,068) between 2006 and 2008 in 717 rehabilitation facilities across the United States. Facilities were assigned to quintiles based on average annual diagnosis-specific patient volumes.
  
  
  METHODS
  Discharge functional status (FIM instrument) and probability of home discharge.
  
  
  RESULTS
  Facility-level factors accounted for 6%-15% of the variance in discharge FIM total scores and 3%-5% of the variance in home discharge probability across the 3 diagnostic groups. We used the middle volume quintile (Q3) as the reference group for all analyses and detected small, but statistically significant (P<0.01) associations with discharge functional status in all 3 diagnosis groups. Only the highest volume quintile (Q5) reached statistical significance, displaying higher functional status ratings than Q3 each time. The largest effect was observed in FIM total scores among fracture patients, with only a 3.6-point difference in Q5 and Q3 group means. Volume was not independently related to home discharge.
  
  
  CONCLUSIONS
  Outcome-specific volume effects ranged from small (functional status) to none (home discharge) in all 3 diagnostic groups. Patients with these conditions can be treated locally rather than at higher volume regional centers. Further regionalization of inpatient rehabilitation services is not needed for these conditions.
authors.affiliation: Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston, TX 77555-1137, USA. jegraham@utmb.edu
authors.forename: James E
authors.initials: JE
authors.lastname: Graham
authors.forename: Anne
authors.initials: A
authors.lastname: Deutsch
authors.forename: Ann A
authors.initials: AA
authors.lastname: O'Connell
authors.forename: Amol M
authors.initials: AM
authors.lastname: Karmarkar
authors.forename: Carl V
authors.initials: CV
authors.lastname: Granger
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ottenbacher
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000534:rehabilitation*; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D003953:Diagnosis-Related Groups; D005260:Female; D050723:Fractures, Bone / Q000534:rehabilitation*; D006302:Health Services Research; D006801:Humans; D007297:Inpatients / Q000706:statistics & numerical data*; D007902:Length of Stay / Q000706:statistics & numerical data; D016014:Linear Models; D035002:Lower Extremity / Q000293:injuries*; D008297:Male; D010351:Patient Discharge / Q000706:statistics & numerical data*; D020127:Recovery of Function; D000071939:Stroke Rehabilitation; D014481:United States