title: Age and obesity are risk factors for adverse events after total hip arthroplasty.
abstract: BACKGROUND
  Defining the epidemiology of adverse events after THA will aid in the development of strategies to enhance perioperative care.
  
  
  OBJECTIVE
  We identified (1) risk factors for adverse events in Medicare beneficiaries while hospitalized after THA and (2) trends in the rates of adverse events.
  
  
  METHODS
  Data were abstracted from medical records of 1809 Medicare beneficiaries who underwent THA from 2002 to 2007. We used the hierarchical generalized linear modeling approach to assess the odds of change in adverse events over time, the association of adverse events with outcomes, and the relationship of adverse events with patient characteristics by modeling the log-odds of adverse events as a function of demographic and clinical variables adjusted for year variable.
  
  
  RESULTS
  The overall rate of adverse events was 5.8%; the 30-day mortality rate was 1.00%. Increased age, obesity, and year of procedure were risk factors for experiencing any adverse event. Annual rates of adverse events from 2002 to 2007 were 9.1%, 8.2%, 4.9%, 4.1%, 3.5%, and 3.0%, respectively. Experiencing any adverse event was associated with an increased length of stay and an increased chance of readmission but not with an increased chance of mortality. The annual rate of all adverse events decreased from 2002-2004 to 2005-2007 (odds ratio = 0.83; 95% confidence interval, 0.74-0.92).
  
  
  CONCLUSIONS
  Older and obese patients should be counseled regarding their increased risk for the development of adverse events after THA. The cause of the decline in the rate of adverse events between two time periods is unclear and warrants further investigation to confirm and identify the cause.
authors.affiliation: Department of Orthopaedic Surgery, Stanford Medicine Outpatient Center, 450 Broadway Street, Mailcode 6324, Redwood City, CA 94063, USA. jhuddleston@stanford.edu
authors.forename: James I
authors.initials: JI
authors.lastname: Huddleston
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Carlos
authors.initials: C
authors.lastname: Uquillas
authors.forename: James H
authors.initials: JH
authors.lastname: Herndon
authors.forename: William J
authors.initials: WJ
authors.lastname: Maloney
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation / Q000401:mortality; D016009:Chi-Square Distribution; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006622:Hip Prosthesis; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D007902:Length of Stay; D016014:Linear Models; D008297:Male; D006278:Medicare; D008875:Middle Aged; D009765:Obesity / Q000209:etiology*; D016017:Odds Ratio; D010359:Patient Readmission; D011183:Postoperative Complications / Q000209:etiology* / Q000401:mortality; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology