Birth defects surveillance: assessing the "gold standard".

Abstract
OBJECTIVES: This study assessed the sensitivity of the Metropolitan Atlanta Congenital Defects Program (MACDP) by capitalizing on the delayed receipt of a data source. METHODS: In 1997, we reviewed the medical records of potential cases from the 1995 birth certificates that had not previously been identified by the MACDP. Capture-recapture methods produced an estimate of total cases. RESULTS: We identified 1149 infants with defects, including 20 exclusively from birth certificates. The estimated sensitivity of the MACDP when data from birth certificates were included was 86.9% (95% confidence interval [CI] = 80.6%, 91.9%) at 1 year after birth, increasing to 94.8% (95% CI = 90.3%, 97.8%) at 2 years after birth. CONCLUSIONS: The MACDP underestimates defects by 13% at 1 year after birth and by 5% at 2 years after birth.