title: Clinical characteristics and outcomes of Medicare patients undergoing total hip arthroplasty, 1991-2008.
abstract: BACKGROUND
  Total hip arthroplasty is a common surgical procedure but little is known about longitudinal trends.
  
  
  OBJECTIVE
  To examine demographics and outcomes of patients undergoing primary and revision total hip arthroplasty.
  
  
  METHODS
  Observational cohort of 1,453,493 Medicare Part A beneficiaries who underwent primary total hip arthroplasty and 348,596 who underwent revision total hip arthroplasty. Participants were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes for primary and revision total hip arthroplasty between 1991 and 2008.
  
  
  METHODS
  Changes in patient demographics and comorbidity, hospital length of stay (LOS), mortality, discharge disposition, and all-cause readmission rates.
  
  
  RESULTS
  Between 1991 and 2008, the mean age for patients undergoing primary total hip arthroplasty increased from 74.1 to 75.1 years and for revision total hip arthroplasty from 75.8 to 77.3 years (P < .001). The mean number of comorbid illnesses per patient increased from 1.0 to 2.0 for primary total hip arthroplasty and 1.1 to 2.3 for revision (P < .001). For primary total hip arthroplasty, mean hospital LOS decreased from 9.1 days in 1991-1992 to 3.7 days in 2007-2008 (P = .002); unadjusted in-hospital and 30-day mortality decreased from 0.5% to 0.2% and from 0.7% to 0.4%, respectively (P < .001). The proportion of primary total hip arthroplasty patients discharged home declined from 68.0% to 48.2%; the proportion discharged to skilled care increased from 17.8% to 34.3%; and 30-day all-cause readmission increased from 5.9% to 8.5% (P < .001). For revision total hip arthroplasty, similar trends were observed in hospital LOS, in-hospital mortality, discharge disposition, and hospital readmission rates.
  
  
  CONCLUSIONS
  Among Medicare beneficiaries who underwent primary and revision hip arthroplasty between 1991 and 2008, there was a decrease in hospital LOS but an increase in the rates of discharge to postacute care and readmission.
authors.affiliation: Division of General Internal Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA. peter-cram@uiowa.edu
authors.forename: Peter
authors.initials: P
authors.lastname: Cram
authors.forename: Xin
authors.initials: X
authors.lastname: Lu
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kaboli
authors.forename: Mary S
authors.initials: MS
authors.lastname: Vaughan-Sarrazin
authors.forename: Xueya
authors.initials: X
authors.lastname: Cai
authors.forename: Brian R
authors.initials: BR
authors.lastname: Wolf
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
mesh_terms: D000359:Aftercare / Q000706:statistics & numerical data; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007902:Length of Stay; D008297:Male; D016344:Medicare Part A / Q000706:statistics & numerical data*; D017063:Outcome Assessment, Health Care; D010351:Patient Discharge / Q000706:statistics & numerical data*; D010359:Patient Readmission / Q000706:statistics & numerical data*; D012086:Reoperation; D014481:United States