title: Validity of a rheumatic disease diagnosis in the Medical Birth Registry of Norway.
abstract: BACKGROUND
  In our population-based study of pregnancy outcome in women with rheumatic disease we based our assessment on the Medical Birth Registry of Norway (MBRN). We evaluated the MBRN as a source of data for such epidemiologic research by assessing the validity of a diagnosis of rheumatic disease in the MBRN against a gold standard. The validity may also be interpreted as a quality indicator, reflecting an obstetrician's attention to rheumatic diseases in pregnancy.
  
  
  METHODS
  Using the mother's national identification number the MBRN was linked with local hospital databases (gold standard), which contained data of mothers with rheumatic disease. The sensitivity of the MBRN was calculated as the proportion of all cases registered locally with a diagnosis of rheumatic disease notified to the MBRN. The correctness of type differentiation was calculated as the proportion of all cases notified to the MBRN that was correct with respect to the type of rheumatic disease.
  
  
  RESULTS
  Among 169 mothers, 149 had a diagnosis in the MBRN, representing a sensitivity of 88.2%. Altogether, 97.3% of the diagnoses (145/149) were correct with respect to the type of rheumatic disease.
  
  
  CONCLUSIONS
  Taken in to consideration the limitations of the study, namely the small numbers studied, we assume a rather high validity of rheumatic disease diagnoses in the MBRN, probably reflecting a high level of attention in the obstetric care for these patients.
authors.affiliation: Department of Rheumatology, Center for Mothers with Rheumatic Diseases, University Hospital of Trondheim, 7006 Trondheim, Norway. johan.skomsvoll@medisin.ntnu.no
authors.forename: Johan
authors.initials: J
authors.lastname: Skomsvoll
authors.forename: Monika
authors.initials: M
authors.lastname: Østensen
authors.forename: Valborg
authors.initials: V
authors.lastname: Baste
authors.forename: Lorentz
authors.initials: L
authors.lastname: Irgens
mesh_terms: D005260:Female; D006801:Humans; D009664:Norway; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011256:Pregnancy Outcome; D019984:Quality Indicators, Health Care; D012042:Registries / Q000592:standards*; D015203:Reproducibility of Results; D012216:Rheumatic Diseases / Q000175:diagnosis*; D012680:Sensitivity and Specificity