title: Association of hospital and surgeon procedure volume with patient-centered outcomes of total knee replacement in a population-based cohort of patients age 65 years and older.
abstract: OBJECTIVE
  To study the association between procedure volume and patient-centered outcomes such as functional status.
  
  
  METHODS
  We performed an observational study of a stratified random sample of Medicare beneficiaries who underwent primary total knee replacement (TKR) in 2000. Low-volume surgeons were defined as surgeons performing < or =6 TKRs per year in the Medicare population, and low-volume centers were defined as those in which < or =25 TKRs per year were performed. The primary outcome was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) functional status score (0-100 scale; 100 = best) 2 years after TKR. We defined a WOMAC functional status score of <60 as a poor functional outcome. Analyses were adjusted for sociodemographic factors, preoperative functional status, and comorbidities.
  
  
  RESULTS
  Fifty-eight percent of 1,597 eligible patients agreed to participate. Twelve percent of participating patients had a WOMAC score <60 2 years following TKR. Patients operated upon by low-volume surgeons in low-volume hospitals were twice as likely to have a poor WOMAC functional status score as patients operated upon by higher volume surgeons and in higher volume hospitals (odds ratio 2.1, 95% confidence interval 1.1-4.2).
  
  
  CONCLUSIONS
  Patients operated upon in low-volume hospitals by low-volume surgeons had worse functional outcomes 2 years after TKR. These findings add a new and important dimension to the discussion of whether to promote selective referral of procedures such as TKR to high-volume centers.
authors.affiliation: Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. jnkatz@partners.org
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Mahomed
authors.forename: John A
authors.initials: JA
authors.lastname: Baron
authors.forename: Jane A
authors.initials: JA
authors.lastname: Barrett
authors.forename: Anne H
authors.initials: AH
authors.lastname: Fossel
authors.forename: Alisha H
authors.initials: AH
authors.lastname: Creel
authors.forename: John
authors.initials: J
authors.lastname: Wright
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Wright
authors.forename: Elena
authors.initials: E
authors.lastname: Losina
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000706:statistics & numerical data*; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D006306:Health Surveys; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data; D009985:Orthopedics / Q000706:statistics & numerical data; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery*; D010043:Outcome and Process Assessment, Health Care / Q000379:methods*; D018802:Patient-Centered Care / Q000706:statistics & numerical data*; D012720:Severity of Illness Index; D016896:Treatment Outcome