title: Hip arthroplasty in Norway 1989-2008.
abstract: BACKGROUND
  Since information on regional variation in the frequency of primary total hip arthroplasty in Norway is scarce, we studied differences by county and regional health authority throughout the last 20 years.
  
  
  METHODS
  We included 112, 514 primary total hip arthroplasties reported to the Norwegian Arthroplasty Register in the years 1989-2008. Annual gender and age standardized frequencies were calculated, and Poisson regression was used for group comparisons (RR = rate ratio).
  
  
  RESULTS
  We observed an increase in hip arthroplasty frequency from 109 operations per 100, 000 inhabitants in the years 1991-1995 to 140 in 2006-2008 (RR = 1.28), and more so for operations performed due to coxarthrosis (RR = 1.46). An increased frequency over time was evident in all five regions and 19 counties. Differences between counties and regions had decreased throughout the study period. In the years 2006-2008, Helse Midt (152 operations) had a statistically significant higher frequency than the other regions except for Helse Sør. The lowest frequencies at county level were found for Finnmark (116 operations) and the highest for Aust-Agder (172).
  
  
  CONCLUSIONS
  While regional differences have decreased since the early 1990 s, existing differences may in part be due to differing access to surgery, varying indications for surgery, or possibly also genetic or cultural differences.
authors.affiliation: Department of Orthopaedic Surgery, Haukeland University Hospital, Norway. birgitte.espehaug@helse-bergen.no
authors.forename: Birgitte
authors.initials: B
authors.lastname: Espehaug
authors.forename: Ove
authors.initials: O
authors.lastname: Furnes
authors.forename: Lars Birger
authors.initials: LB
authors.lastname: Engesæter
authors.forename: Leif Ivar
authors.initials: LI
authors.lastname: Havelin
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000592:standards / Q000706:statistics & numerical data / Q000639:trends; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D016012:Poisson Distribution; D012086:Reoperation; D012737:Sex Factors