title: Association between hospital procedure volume and risk of revision after total hip arthroplasty: a population-based study within the Nordic Arthroplasty Register Association database.
abstract: OBJECTIVE
  Outcome after total hip arthroplasty (THA) depends on several factors related to the patient, the surgeon and the implant. It has been suggested that the annual number of procedures per hospital affects the prognosis. We aimed to examine if hospital procedure volume was associated with the risk of revision after primary THA in the Nordic countries from 1995 to 2011.
  
  
  METHODS
  The Nordic Arthroplasty Register Association database provided information about primary THA, revision and annual hospital volume. Hospitals were divided into five volume groups (1-50, 51-100, 101-200, 201-300, >300). The outcome of interest was risk of revision 1, 2, 5, 10 and 15 years after primary THA. Multivariable regression was used to assess the relative risk (RR) of revision.
  
  
  RESULTS
  417,687 THAs were included. For the 263,176 cemented THAs no differences were seen 1 year after primary procedure. At 2, 5, 10 and 15 years the four largest hospital volume groups had a reduced risk of revision compared to group 1-50. After 10 years RR was for volume group 51-100 0.79 (CI 0.65-0.95), group 101-200 0.76 (CI 0.61-0.95), group 201-300 0.74 (CI 0.57-0.96) and group >300 0.57 (CI 0.46-0.71). For the uncemented THAs an association between hospital volume and risk of revision were only present for hospitals producing 201-300 THAs per year, beginning at years 2 through 5 and in all subsequent time intervals to 15 years.
  
  
  CONCLUSIONS
  Hospital procedure volume was associated with a long term risk of revision after primary cemented THA. Hospitals operating 50 procedures or less per year had an increased risk of revision after 2, 5, 10 and 15 years follow up.
authors.affiliation: University Clinic for Hand, Hip and Knee Surgery, Regional Hospital West Jutland, Aarhus University, Denmark; Department of Clinical Epidemiology, Aarhus University Hospital, Denmark. Electronic address: evagla@rm.dk.
authors.forename: E N
authors.initials: EN
authors.lastname: Glassou
authors.affiliation: University Clinic for Hand, Hip and Knee Surgery, Regional Hospital West Jutland, Aarhus University, Denmark. Electronic address: torhas@rm.dk.
authors.forename: T B
authors.initials: TB
authors.lastname: Hansen
authors.affiliation: Department of Orthopaedics and Traumatology, Turku University Hospital, Turku, Finland. Electronic address: Keijo.Makela@tyks.fi.
authors.forename: K
authors.initials: K
authors.lastname: Mäkelä
authors.affiliation: The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway. Electronic address: leif.ivar.havelin@helse-bergen.no.
authors.forename: L I
authors.initials: LI
authors.lastname: Havelin
authors.affiliation: The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway. Electronic address: ove.nord.furnes@helse-bergen.no.
authors.forename: O
authors.initials: O
authors.lastname: Furnes
authors.affiliation: Kysthospital in Hagavik, Haukeland University Hospital, Bergen, Norway. Electronic address: mona.badawy@helse-bergen.no.
authors.forename: M
authors.initials: M
authors.lastname: Badawy
authors.affiliation: Institute of Clinical Sciences, Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden; Swedish Hip Arthroplasty Register, Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden. Electronic address: johan.karrholm@vgregion.se.
authors.forename: J
authors.initials: J
authors.lastname: Kärrholm
authors.affiliation: Institute of Clinical Sciences, Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden; Swedish Hip Arthroplasty Register, Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden. Electronic address: goran.garellick@registercentrum.se.
authors.forename: G
authors.initials: G
authors.lastname: Garellick
authors.affiliation: Coxa Hospital for Joint Replacement, Tampere, Finland. Electronic address: antti.eskelinen@coxa.fi.
authors.forename: A
authors.initials: A
authors.lastname: Eskelinen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Denmark. Electronic address: abp@clin.au.dk.
authors.forename: A B
authors.initials: AB
authors.lastname: Pedersen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods / Q000706:statistics & numerical data*; D002484:Cementation; D002648:Child; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D011475:Prosthesis Failure; D012042:Registries; D012086:Reoperation / Q000706:statistics & numerical data*; D012307:Risk Factors; D012537:Scandinavian and Nordic Countries; D016526:Workload / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Adverse event; Hospital volume; Joint revision; Osteoarthritis; Total hip arthroplasty