title: Infection after primary hip arthroplasty: a comparison of 3 Norwegian health registers.
abstract: OBJECTIVE
  The aim of the present study was to assess incidence of and risk factors for infection after hip arthroplasty in data from 3 national health registries. We investigated differences in risk patterns between surgical site infection (SSI) and revision due to infection after primary total hip arthroplasty (THA) and hemiarthroplasty (HA).
  
  
  METHODS
  This observational study was based on prospective data from 2005-2009 on primary THAs and HAs from the Norwegian Arthroplasty Register (NAR), the Norwegian Hip Fracture Register (NHFR), and the Norwegian Surveillance System for Healthcare-Associated Infections (NOIS). The Norwegian Patient Register (NPR) was used for evaluation of case reporting. Cox regression analyses were performed with revision due to infection as endpoint for data from the NAR and the NHFR, and with SSI as the endpoint for data from the NOIS.
  
  
  RESULTS
  The 1-year incidence of SSI in the NOIS was 3.0% after THA (167/5,540) and 7.3% after HA (103/1,416). The 1-year incidence of revision due to infection was 0.7% for THAs in the NAR (182/24,512) and 1.5% for HAs in the NHFR (128/8,262). Risk factors for SSI after THA were advanced age, ASA class higher than 2, and short duration of surgery. For THA, the risk factors for revision due to infection were male sex, advanced age, ASA class higher than 1, emergency surgery, uncemented fixation, and a National Nosocomial Infection Surveillance (NNIS) risk index of 2 or more. For HAs inserted after fracture, age less than 60 and short duration of surgery were risk factors of revision due to infection.
  
  
  CONCLUSIONS
  The incidences of SSI and revision due to infection after primary hip replacements in Norway are similar to those in other countries. There may be differences in risk pattern between SSI and revision due to infection after arthroplasty. The risk patterns for revision due to infection appear to be different for HA and THA.
authors: The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway. haavard.dale@helse-bergen.no
authors: Håvard
authors: H
authors: Dale
authors: Inge
authors: I
authors: Skråmm
authors: Hege L
authors: HL
authors: Løwer
authors: Hanne M
authors: HM
authors: Eriksen
authors: Birgitte
authors: B
authors: Espehaug
authors: Ove
authors: O
authors: Furnes
authors: Finn Egil
authors: FE
authors: Skjeldestad
authors: Leif I
authors: LI
authors: Havelin
authors: Lars B
authors: LB
authors: Engesaeter
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D011446:Prospective Studies; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000453:epidemiology / Q000209:etiology*; D012042:Registries; D012086:Reoperation; D012307:Risk Factors