title: Case mix and outcomes of total knee replacement in orthopaedic specialty hospitals.
abstract: OBJECTIVE
  To examine patient characteristics and outcomes of total knee replacement (TKR) in orthopaedic specialty hospitals.
  
  
  METHODS
  We performed a retrospective cohort study in the US Medicare population. We defined specialty hospitals for TKR as centers: (1) that performed >75 TKRs in Medicare recipients in 2000; (2) in which TKR accounted for >7% of all Medicare discharges; and (3) that had <300 beds. We divided specialty hospitals into those with <or=100 beds and those with 101-299 beds. We compared preoperative characteristics and complications among patients undergoing TKR in specialty and nonspecialty centers. We stratified patients according to risk of complications and performed stratum-specific analyses.
  
  
  RESULTS
  A total of 2,417 patients received TKA in 19 specialty hospitals, accounting for 3% of all TKRs in 2000. The specialty hospitals had fewer patients with poverty level income. The smaller "boutique" specialty hospitals had lower complication rates than the larger specialty hospitals and the nonspecialty centers (P value for trend = 0.001). In analyses that adjusted for patient age and sex, low-risk patients had similar outcomes across all hospital categories. However, high-risk patients had statistically significantly greater benefit from treatment in smaller specialty hospitals, with the risk of any adverse event ranging from 1.4% (95% CI, 0%-3.5%) in smaller specialty hospitals to 4.9% (95% CI, 4.4%-5.5%) in low-volume centers.
  
  
  CONCLUSIONS
  Smaller specialty hospitals have low complication rates and are especially beneficial for high-risk patients. Further work should address functional outcomes, costs, and satisfaction in these specialty centers, and evaluate strategies to manage more high-risk patients in specialty centers.
authors.affiliation: Immunology, and Allergy, Orthopaedic and Arthritis Center for Outcomes Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. jnkatz@partners.org
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Bierbaum
authors.forename: Elena
authors.initials: E
authors.lastname: Losina
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000706:statistics & numerical data*; D003953:Diagnosis-Related Groups; D005260:Female; D006782:Hospitals, Special / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D006278:Medicare; D008875:Middle Aged; D009985:Orthopedics; D011183:Postoperative Complications / Q000453:epidemiology; D012189:Retrospective Studies; D012923:Social Class; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology