title: Validity of pre-eclampsia registration in the medical birth registry of norway for women participating in the norwegian mother and child cohort study, 1999-2010.
abstract: BACKGROUND
  The Norwegian Mother and Child Cohort Study (MoBa), a prospective population-based pregnancy cohort, is a valuable database for studying causes of pre-eclampsia. Pre-eclampsia data in MoBa come from the Medical Birth Registry of Norway (MBRN); thus, we wanted to study the validity of MBRN pre-eclampsia registration for MoBa women.
  
  
  METHODS
  We selected all MoBa pregnancies with pre-eclampsia registered in the MBRN (n = 4081) and a random control group (n = 2000) without pre-eclampsia registrations. After excluding two delivery units not participating in MoBa and one no longer operating, units were asked to provide copies of antenatal charts with blood pressure and urinary measurements from all antenatal visits during pregnancy, and hospital discharge codes from the delivery stay. We received data for 5340 pregnancies delivered 1999-2010 (87% of all eligible). We calculated positive predictive value (PPV), and sensitivity and specificity of MBRN registration, using hypertension and proteinuria on the antenatal charts and/or hospital discharge codes indicating pre-eclampsia as gold standard.
  
  
  RESULTS
  Overall PPV was 83.9% [95% CI 82.7, 85.1] and was higher when women were primiparous, or delivered preterm or low birthweight infants. Severe pre-eclampsia in the MBRN was found to be a true severe pre-eclampsia in 70% of cases. Extrapolating to the total MoBa population, the estimated sensitivity was low - 43.0% (38.7, 48.2) - while specificity was high - 99.2% (99.2, 99.3). False negative cases seemed to have mild forms of pre-eclampsia.
  
  
  CONCLUSIONS
  PPV and specificity of pre-eclampsia registration in the MBRN during 1999-2010 was satisfactory, while sensitivity was low.
authors.affiliation: Medical Birth Registry of Norway, Division of Epidemiology, Norwegian Institute of Public Health, Bergen, Norway; Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors.forename: Kari
authors.initials: K
authors.lastname: Klungsøyr
authors.forename: Quaker E
authors.initials: QE
authors.lastname: Harmon
authors.forename: Linn B
authors.initials: LB
authors.lastname: Skard
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Simonsen
authors.forename: Elise T
authors.initials: ET
authors.lastname: Austvoll
authors.forename: Elin R
authors.initials: ER
authors.lastname: Alsaker
authors.forename: Anne
authors.initials: A
authors.lastname: Starling
authors.forename: Lill
authors.initials: L
authors.lastname: Trogstad
authors.forename: Per
authors.initials: P
authors.lastname: Magnus
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Engel
mesh_terms: D016022:Case-Control Studies; D005260:Female; D006801:Humans; D009664:Norway / Q000453:epidemiology; D011225:Pre-Eclampsia / Q000175:diagnosis* / Q000453:epidemiology; D011247:Pregnancy; D012042:Registries; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity
keywords: Pre-eclampsia; predictive value; registry; sensitivity; specificity; validation study