Predictive value and completeness of the registration of congenital abnormalities in three Danish population-based registries

AIMS: The predictive value and completeness of data on congenital abnormalities (CAs) collected in three administrative health registries in the County of North Jutland, Denmark were compared.

METHODS: The study included all singleton liveborn infants in the county during the period 1991-94 (n = 24,147). All infants recorded as having a CA in either the Medical Birth Registry (MBR), the Hospital Discharge Registry (HDR), or the National Registry of Congenital Abnormalities (NRCA) were identified, and the recordings in each registry were compared. Infants recorded in at least two registries were considered correctly diagnosed with a CA for the sake of the analyses. The predictive value was defined as the number of infants correctly diagnosed with a CA in the registry divided by the total number of infants recorded with a CA in the registry. In all cases with recording in one registry only, the predictive value of the registration with CA diagnosis was assessed through a review of a sample of medical records. The completeness was defined as the number of correctly diagnosed CAs in the registry divided by the total number of identified CAs.

RESULTS: The predictive value and completeness were calculated as 89.1% (85.3-92.8) and 32.3% (28.9-35.7) in the MBR; 88.2% (85.9-90.5) and 89.9% (87.7-92.1) in the HDR; and 99.6% (98.9-100.0) and 36.0% (32.5-39.5) in the NRCA.

CONCLUSIONS: The HDR seems to have a predictive value and completeness that are acceptable for general surveillance and epidemiological research regarding CAs. The NRCA may be suitable for case-control studies owing to a high predictive value.