Problems in using birth certificate files in the capture-recapture model to estimate the completeness of case ascertainment in a population-based birth defects registry in New York State.
BACKGROUND
The limitations and underlying assumptions of the capture-recapture methods have hindered their application in epidemiological settings, especially in evaluating the completeness of birth defects registries. This study explored the possibility of using birth certificates as the secondary data source in a simple two-source capture-recapture model to estimate the completeness of case ascertainment of the Congenital Malformations Registry (CMR) for selected major birth defects.


METHODS
The CMR and the birth certificates were used as the primary and secondary sources, respectively. Children who were born in 1996-2001 and had selected major birth defects were identified from the two sources. The accuracy of the diagnoses was examined by comparing the individual birth defect categories of the children from the two sources.


RESULTS
Discrepancies in birth defect categories in the two data sources and false positives in the birth certificates were the major problems encountered in estimating the completeness of the CMR using the simple two-source capture-recapture method. The estimated completeness for selected major birth defects was only about 71%. Stratified analyses resulted in relatively high estimated completeness for oral clefts (90%) and Down syndrome (88%). CONCLUSIONS Although the birth certificate data was not a good source for estimating the completeness of case ascertainment of the CMR using capture-recapture methods, the analyses provided reasonable estimates for some conditions that were relatively easy to identify and diagnose at birth, such as oral clefts and Down syndrome.
Wang
Ying
Y
Congenital Malformations Registry, Center for Environmental Health, New York State Department of Health, Troy, New York 12180-2216, USA. wxy01@health.state.ny.us
Druschel
Charlotte M
CM
Cross
Philip K
PK
Hwang
Syni-An
SA
Gensburg
Lenore J
LJ
D001719:Birth Certificates; D000013:Congenital Abnormalities / Q000453:epidemiology*; D006801:Humans; D007231:Infant, Newborn; D015233:Models, Statistical; D009518:New York / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods*; D012042:Registries; D015203:Reproducibility of Results