The methodology of the Utah Birth Defect Network: Congenital heart defects as an illustration

OBJECTIVES: The Utah Birth Defect Network (UBDN) uses a population-based birth defect surveillance system that has evolved from identifying only neural tube defects in 1994 to monitoring all structural malformations since 1999. All pregnancy outcomes are monitored statewide through intensive identification of potential cases using multiple reporting sources. METHODS: The UBDN is a well-established statewide surveillance system that uses a combined approach, active and passive, in case ascertainment. Utah has the distinct advantage of having relatively few points of entry into the health care system both pre- and postnatally. A description of the UBDN methodology is presented and the completeness, validity and timing of reporting sources and diagnoses are illustrated using the example of congenital heart defects (CHD). RESULTS: The UBDN identified a total of 2,115 potential CHD cases, of which 1,082 (51.2%) were determined to be true cases and 1,033 (48.8%) were classified as not a case (NAC). A single source was responsible for reporting 1,038 (49.1%) potential cases: 241 (23.2%) were true cases, and the remaining 797 (76.8%) were classified as NAC and considered to be false positives. DISCUSSION: This descriptive analysis of CHD cases collected through the UBDN's surveillance system illustrates the necessity-and benefit-of using multiple sources of ascertainment to ensure completeness of reporting.