title: Validity of the diagnosis of pre-eclampsia in the Medical Birth Registry of Norway.
abstract: OBJECTIVE
  Evaluating the validity of pre-eclampsia registration in the Medical Birth Registry of Norway (MBRN) according to both broader and restricted disease definitions.
  
  
  METHODS
  Retrospective nested cohort study.
  
  
  METHODS
  Multicenter study.
  
  
  METHODS
  In this study, two cohorts of women with pre-eclamptic pregnancies registered in the MBRN were selected. Study group 1 contained 966 pregnancies from 1967 to 2002. Concomitant participation in the Nord-Trøndelag Health Study 2 was required. Study group 2 comprised 1138 pregnancies recorded in 1967-2005, examined as a pre-eclampsia biobank was established.
  
  
  METHODS
  Diagnostic criteria vary. The broader criteria for pre-eclampsia, used by the MBRN, are one measurement of hypertension and proteinuria (Criterion A). Criteria used internationally today require two measurements of hypertension and proteinuria (Criterion B). The diagnostic validities in Study groups 1 and 2 were judged against medical records according to Criterion A and B, respectively.
  
  
  METHODS
  Positive predictive value (PPV) and trend analyses.
  
  
  RESULTS
  The diagnosis was confirmed in 88.3% of pregnancies in Study group 1, and in 63.6% in Study group 2. PPV was high for Study group 1 throughout the period. For Study group 2, results improved significantly after 1986.
  
  
  CONCLUSIONS
  This study ascertains high PPV of pre-eclampsia in the MBRN using broader traditional criteria, although the PPV decreases through assessment using restricted modern criteria. This illustrates how inclusion of direct measurements may improve registration of complex disorders defined by changing diagnostic criteria.
authors.affiliation: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway. Liv.Vestrheim@med.uib.no
authors.forename: Liv C V
authors.initials: LC
authors.lastname: Thomsen
authors.forename: Kari
authors.initials: K
authors.lastname: Klungsøyr
authors.forename: Linda T
authors.initials: LT
authors.lastname: Roten
authors.forename: Christian
authors.initials: C
authors.lastname: Tappert
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Araya
authors.forename: Gunhild
authors.initials: G
authors.lastname: Baerheim
authors.forename: Kjersti
authors.initials: K
authors.lastname: Tollaksen
authors.forename: Mona H
authors.initials: MH
authors.lastname: Fenstad
authors.forename: Ferenc
authors.initials: F
authors.lastname: Macsali
authors.forename: Rigmor
authors.initials: R
authors.lastname: Austgulen
authors.forename: Line
authors.initials: L
authors.lastname: Bjørge
mesh_terms: D015331:Cohort Studies; D005260:Female; D006801:Humans; D009664:Norway / Q000453:epidemiology; D011225:Pre-Eclampsia / Q000175:diagnosis* / Q000453:epidemiology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D012042:Registries; D012189:Retrospective Studies
keywords: Antenatal care and diagnosis; Medical Birth Registry of Norway; evaluation of diagnostic criteria; health registry data; hypertension in pregnancy; pre-eclampsia; validation of diagnosis