title: Positive predictive value and completeness of prenatally assigned International Classification of Disease-10 kidney anomaly diagnoses in the Danish National Patient Registry.
abstract: OBJECTIVE
  Restricting studies of severe congenital malformations to live-born children may introduce substantial bias. In this study, we estimated the attendance to the second-trimester fetal malformation screening program. We also estimated the positive predictive value (PPV) of prenatally assigned International Classification of Disease-10 diagnoses recorded in the Danish National Patient Registry (DNPR) and the completeness of case registration. We used kidney anomalies as an example.
  
  
  METHODS
  We identified the proportion of all Danish live-born children from January 1, 2007 to December 31, 2012, who were scanned during the second trimester using the DNPR and the Civil Registration System. Details of all fetuses with specific kidney anomaly diagnoses according to the DNPR were retrieved. The PPV was estimated using the nationwide Astraia database of pregnancy medical charts or traditional medical charts, as gold standard. The completeness was assessed using the total number of cases estimated by the capture-recapture method.
  
  
  RESULTS
  Of 372,263 live born infants, 97.3% were scanned during the second trimester. We identified 172 fetuses in the DNPR. Of these, 149 had kidney anomalies according to Astraia or medical chart review, corresponding to a PPV of 87% (95% CI: 81%-91%). The estimated completeness was 43% (95% CI: 38%-49%) for the DNPR and 75% (95% CI: 70%-79%) for Astraia.
  
  
  CONCLUSIONS
  Almost all live-born children were scanned during the second trimester in Denmark. However, low completeness may hamper the use of the DNPR for studies of prenatally detected severe malformations, and use of the Astraia database may preferably be considered.
authors: Department of Clinical Genetics, Aarhus University Hospital, Skejby, Denmark.
authors: Maria
authors: M
authors: Rasmussen
authors: Department of Clinical Epidemiology, Aarhus University Hospital, Skejby, Denmark.
authors: Morten Smærup
authors: MS
authors: Olsen
authors: Department of Clinical Genetics, Aarhus University Hospital, Skejby, Denmark; Department of Biomedicine, Aarhus University, Aarhus, Denmark.
authors: Lone
authors: L
authors: Sunde
authors: Department of Clinical Epidemiology, Aarhus University Hospital, Skejby, Denmark.
authors: Lars
authors: L
authors: Pedersen
authors: Department of Gynecology and Obstetrics, Aarhus University Hospital, Skejby, Denmark.
authors: Olav Bjørn
authors: OB
authors: Petersen
keywords: Astraia; Danish Fetal Medicine Database; Danish National Patient Registry; International Classification of Disease; kidney anomaly; prenatal diagnosis; validation study