title: Short-term Risk of Revision THA in the Medicare Population Has Not Improved With Time.
abstract: BACKGROUND
  Advances in surgical technique, implant design, and clinical care pathways have resulted in higher expectations for improved clinical outcomes after primary THA; however, despite these advances, it is unclear whether the risk of revision THA actually has decreased with time. Understanding trends in short- and mid-term risks of revision will be helpful in directing clinical, research, and policy efforts to improve THA outcomes.
  
  
  OBJECTIVE
  We therefore asked (1) whether there have been changes in overall short- and mid-term risks of revision THA among patients in the Medicare population who underwent primary THA between 1998 and 2010; and (2) whether there are different demographic factors associated with short- and mid- term risks of revision THA.
  
  
  METHODS
  Using the Medicare 5% national sample database, patients who underwent primary THA between 1998 and 2010 followed by subsequent revision through 2011 were identified by ICD-9-CM procedure codes 81.51 and 81.53/80.05/00.70-00.73, respectively. This dataset included a random sample of Medicare beneficiaries based on their social security number. Only patients with minimum 1-year followup after primary THA were included in our analysis. A total of 64,260 patients who underwent primary THA were identified from the 1998 to 2010 Medicare 5% dataset. Eighty-eight percent of the patients had 1-year followup providing a final study cohort of 56,700 patients. The risk of revision was evaluated at 1, 3, 5, and 7 years. Multivariate Cox regression was used to evaluate temporal trends in revision risk using two methods to account for time effects with periods 1998 to 2002, 2003 to 2007, and 2008 to 2010 for the index year of primary THA, and individual year of index of primary THA as independent variables. The analysis adjusted for patient age, sex, race, census region, Charlson score, and socioeconomic status.
  
  
  RESULTS
  The 7-year crude risk of revision THA declined from 7.10% in 1998 to 2002 to 6.09% in 2008 to 2010, representing a 14.4% overall reduction in adjusted risk of revision (p = 0.0058; 95% CI, 4.4%-23%). Similarly, the 5-year crude risk of revision THA declined from 5.96% in 1998 to 2002 to 5.11% in 2008 to 2010, representing a 14.2% overall reduction in adjusted risk of revision (p = 0.0069; 95% CI, 4.1%-23%). However, the adjusted risk of revision THA at 3 years was not different from 1998 to 2002 (4.70%) and 2008 to 2010 (4.03%; p = 0.1176). Similarly, the adjusted risk of revision at 1 year did not differ from 1998 to 2002 (2.83%) and 2008 to 2010 (2.42%; p = 0.3386). Patients with more comorbidities had a greater adjusted risk of revision (p < 0.001) at all times: 94% (95% CI, 58%-138%) and 56% (95% CI, 33%-84%) at 1 year and 7 years, respectively, for Charlson score of 5+ vs 0).
  
  
  CONCLUSIONS
  Although the mid-term (5 and 7 years) risk of revision THA has decreased during the past 14 years among Medicare beneficiaries who underwent primary THA, the short-term risk has not. These findings suggest that greater clinical, research, and policy emphasis is needed to identify potentially avoidable causes of early failure after primary THA in patients in the Medicare population, and multistakeholder solutions are needed to optimize short-term outcomes.
  
  
  METHODS
  Level III, therapeutic study.
authors.affiliation: Department of Surgery and Preoperative Care, Dell Medical School at University of Texas at Austin, 1912 Speedway, Suite 564, Sanchez Building, Austin, TX, 78712, USA. kevin.bozic@austin.utexas.edu.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Bozic
authors.affiliation: Exponent, Inc, Philadelphia, PA, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Ong
authors.affiliation: Exponent, Inc, Philadelphia, PA, USA.|Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Kurtz
authors.affiliation: Exponent, Inc, Menlo Park, CA, USA.
authors.forename: Edmund
authors.initials: E
authors.lastname: Lau
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Vail
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Harry
authors.initials: H
authors.lastname: Rubash
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Berry
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation* / Q000639:trends; D005260:Female; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D006278:Medicare / Q000639:trends; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000639:trends; D012086:Reoperation / Q000639:trends; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States