title: Validation of the diagnosis 'prosthetic joint infection' in the Danish Hip Arthroplasty Register.
abstract: OBJECTIVE
  The purpose of this study was to validate the diagnosis of periprosthetic joint infection (PJI) in the Danish Hip Arthroplasty Register (DHR).
  
  
  METHODS
  We identified a cohort of patients from the DHR who had undergone primary total hip arthroplasty (THA) since 1 January 2005 and followed them until first-time revision, death, emigration or until 31 December 2012. Revision for PJI, as registered in the DHR, was validated against a benchmark which included information from microbiology databases, prescription registers, clinical biochemistry registers and clinical records. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for PJI in the DHR alone and in the DHR when combined with microbiology databases.
  
  
  RESULTS
  In total, 1382 of the 37 826 primary THAs in the DHR were registered as having been revised for any cause once 26 patients with errors in registration had been excluded: 232 of these were for PJI. For this group, the sensitivity was 67%, specificity 95%, PPV 77%, and NPV 92%. Combining the data from the DHR with those from microbiology databases increased the sensitivity to 90% and also improved specificity (100%), PPV (98%) and NPV (98%).
  
  
  CONCLUSIONS
  Only two thirds of revisions for PJI were captured in the DHR and only 77% of the PJI reported to the DHR could be confirmed to be infected.
  
  
  CONCLUSIONS
  combining the data from the DHR with those from microbiology databases substantially improved the validity of the diagnosis of PJI and should enable future register-based studies.
authors.affiliation: Department of Surgery and Traumatology, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark and, Department of Orthopaedics, Kolding Hospital - a part of Hospital Lillebaelt Skovvangen 2-8, DK-6000 Kolding, Denmark.
authors.forename: P H
authors.initials: PH
authors.lastname: Gundtoft
authors.affiliation: Aarhus University Hospital, Olof Palmes Allé 42-44, DK-8200 Aarhus, Denmark.
authors.forename: A B
authors.initials: AB
authors.lastname: Pedersen
authors.affiliation: Aalborg University Hospital and Department of Clinical Medicine, Aalborg University, Hobrovej 18-22, DK-9100 Aalborg, Denmark.
authors.forename: H C
authors.initials: HC
authors.lastname: Schønheyder
authors.affiliation: Institute of Clinical Research, University of Southern Denmark, Sdr. Boulevard 29, DK-5000 Odense, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Overgaard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D002097:C-Reactive Protein / Q000378:metabolism; D016208:Databases, Factual; D003718:Denmark; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects* / Q000382:microbiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000209:etiology* / Q000382:microbiology; D012042:Registries / Q000592:standards*; D012086:Reoperation / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D002097:C-Reactive Protein
keywords: Arthroplasty; Hip arthroplasty; National Arthroplasty Register; Prosthetic Joint Infection; Validation