title: Relation between surgeon volume and risk of complications after total hip arthroplasty: propensity score matched cohort study.
abstract: OBJECTIVE
  To identify a cut point in annual surgeon volume associated with increased risk of complications after primary elective total hip arthroplasty and to quantify any risk identified.
  
  
  METHODS
  Propensity score matched cohort study.
  
  
  METHODS
  Ontario, Canada.
  
  
  METHODS
  37,881 people who received their first primary total hip arthroplasty during 2002-09 and were followed for at least two years after their surgery.
  
  
  METHODS
  The rates of various surgical complications within 90 days (venous thromboembolism, death) and within two years (infection, dislocation, periprosthetic fracture, revision) of surgery.
  
  
  RESULTS
  Multivariate splines were developed to visualize the relation between surgeon volume and the risk for various complications. A threshold of 35 cases a year was identified, under which there was an increased risk of dislocation and revision. 6716 patients whose total hip arthroplasty was carried out by surgeons who had done ≤ 35 such procedure in the previous year were successfully matched to patients whose surgeon had carried out more than 35 procedures. Patients in the former group had higher rates of dislocation (1.9% v 1.3%, P=0.006; NNH 172) and revision (1.5% v 1.0%, P=0.03; NNH 204).
  
  
  CONCLUSIONS
  In a cohort of first time recipients of total hip arthroplasty, patients whose operation was carried by surgeons who had performed 35 or fewer such procedures in the year before the index procedure were at increased risk for dislocation and early revision. Surgeons should consider performing 35 cases or more a year to minimize the risk for complications. Furthermore, the methods used to visualize the relationship between surgeon volume and the occurrence of complications can be easily applied in any jurisdiction, to help inform and optimize local healthcare delivery.
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Canada bheeshma.ravi@mail.utoronto.ca.
authors.forename: Bheeshma
authors.initials: B
authors.lastname: Ravi
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Jenkinson
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Canada Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Canada.
authors.forename: Ruth
authors.initials: R
authors.lastname: Croxford
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Wasserstein
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Canada.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Escott
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Canada Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Paterson
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Canada Institute for Clinical Evaluative Sciences, Toronto, Canada Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada.
authors.forename: Hans
authors.initials: H
authors.lastname: Kreder
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Canada Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada Division of Rheumatology, Department of Medicine, Women's College Hospital, Toronto, Canada.
authors.forename: Gillian A
authors.initials: GA
authors.lastname: Hawker
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000401:mortality / Q000706:statistics & numerical data*; D002170:Canada / Q000453:epidemiology; D002983:Clinical Competence; D015331:Cohort Studies; D005260:Female; D006302:Health Services Research; D017052:Hospital Mortality; D061846:Hospitals, Low-Volume / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010043:Outcome and Process Assessment, Health Care; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*