Comparison of defects identified through Minnesota's Birth Defects Information System And Vital Records, 2006-2008

The purpose of this study was to examine the differences in birth defects identified through passive and active surveillance systems in Hennepin and Ramsey counties in Minnesota, 2006-2008. This was done by comparing birth defects identified on birth certificates through the Minnesota Department of Health's Office of the State Registrar's Birth and Death Registry (vital records) with those identified by the Minnesota Department of Health's Birth Defects Information System (BDIS), an active birth defects surveillance system. The study population included 73,059 babies born to residents of Hennepin and Ramsey counties. There were 1,882 babies that either vital records and/or BDIS identified as having 1 or more birth defects. Cases identified by BDIS were then linked with matching birth certificates found in the vital records database. Using BDIS as the gold standard, it was observed that the vital records database had an overall underreporting rate of 89% when all broad groups of defects were compared, and 72% when 11 specific defects tracked by both registries were compared. The sensitivity and positive predictive values of vital records to identify cases were also compared using BDIS as the gold standard, and demonstrated low sensitivities for most of the 11 comparable defects (range: 0% for tracheoesophageal fistula to 80% for anencephalus). These observations indicate that BDIS has significantly improved the quality of birth defects surveillance in Minnesota.