Estimating prevalence of fetal alcohol syndrome (FAS): effectiveness of a passive birth defects registry system.

BACKGROUND Fetal alcohol syndrome (FAS) is a preventable birth defect, easiest to recognize in children two through eleven years and more difficult to recognize in newborns. In New York State, two systems ascertain FAS cases, the statewide birth defects registry and the Fetal Alcohol Syndrome Surveillance Network (FASSNet) system. The accuracy of FAS reports to the birth defects registry was assessed through a comparison with the FASSNet system. METHODS The birth defects registry mandates reporting up to age two, including FAS with an ICD-9 code of 760.71. FASSNet is a population-based, multi-source surveillance and uses a standard definition to determine FAS case status. RESULTS Among 33 children reported to the registry with FAS, 19 (58%) met FASSNet criteria for FAS. FASSNet identified 24 additional children with FAS facial features documented before the child's second birthday that should have been reported to the birth defects registry. FAS prevalence rate for the birth defects registry was 0.28 per 1,000 live births but would have been 0.37 if all children diagnosed before age two were included. CONCLUSIONS Almost 60% of children reported to a birth defects registry with FAS from 1995 to 1998 were confirmed as FAS based on a more intensive surveillance. Additional children with FAS were not reported to the CMR. FAS prevalence calculated from birth defects registries, relying on the ICD-9 code 760.71, include false positives and underestimate the true prevalence. Age limits for reporting FAS to registries further contribute to under ascertainment.