title: Retrivability in The Danish National Hospital Registry of HIV and hepatitis B and C coinfection diagnoses of patients managed in HIV centers 1995-2004.
abstract: BACKGROUND
  Hospital-based discharge registries are used increasingly for longitudinal epidemiological studies of HIV. We examined completeness of registration of HIV infections and of chronic hepatitis B (HBV) and hepatitis C (HCV) coinfections in the Danish National Hospital Registry (DNHR) covering all Danish hospitals.
  
  
  METHODS
  The Danish HIV Cohort Study (DHCS) encompasses all HIV-infected patients treated in Danish HIV clinics since 1 January 1995. All 2,033 Danish patients in DHCS diagnosed with HIV-1 during the 10-year period from 1 January 1995 to 31 December 2004 were included in the current analysis. We used the DHCS as a reference to examine the completeness of HIV and of HBV and HCV coinfections recorded in DNHR. Cox regression analysis was used to estimate hazard ratios of time to diagnosis of HIV in DNHR compared to DHCS.
  
  
  RESULTS
  Of the 2,033 HIV patients in DHCS, a total of 2,006 (99%) were registered with HIV in DNHR. Of these, 1,888 (93%) were registered in DNHR within one year of their first positive HIV test. A CD4 < 200 cells/microl, a viral load > or = 100,000 copies/ml and being diagnosed after 1 January 2000, were associated with earlier registration in DNHR, both in crude and adjusted analyses. Thirty (23%) HIV patients registered with chronic HBV (n = 129) in DHCS and 126 (48%) of HIV patients with HCV (n = 264) in DHCS were registered with these diagnoses in the DNHR. Further 17 and 8 patients were registered with HBV and HCV respectively in DNHR, but not in DHCS. The positive predictive values of being registered with HBV and HCV in DHCS were thereby estimated to 0.88 and 0.97 and in DNHR to 0.32 and 0.54.
  
  
  CONCLUSIONS
  The study demonstrates that secondary data from national hospital databases may be reliable for identification of patients diagnosed with HIV infection. However, the predictive value of co-morbidity data may be low.
authors.affiliation: Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. niels.obel@rh.regionh.dk
authors.forename: Niels
authors.initials: N
authors.lastname: Obel
authors.forename: Hanne
authors.initials: H
authors.lastname: Reinholdt
authors.forename: Lars H
authors.initials: LH
authors.lastname: Omland
authors.forename: Frederik
authors.initials: F
authors.lastname: Engsig
authors.forename: Henrik T
authors.initials: HT
authors.lastname: Sørensen
authors.forename: Ann-Brit E
authors.initials: AB
authors.lastname: Hansen
mesh_terms: D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology* / Q000401:mortality; D006509:Hepatitis B / Q000150:complications / Q000453:epidemiology* / Q000401:mortality; D006526:Hepatitis C / Q000150:complications / Q000453:epidemiology* / Q000401:mortality; D006753:Hospital Records; D006801:Humans; D053208:Kaplan-Meier Estimate; D010351:Patient Discharge; D016016:Proportional Hazards Models; D012042:Registries