Congenital heart defect case ascertainment by the Alberta Congenital Anomalies Surveillance System

Abstract

Background: Congenital heart defects (CHDs) are the most common type of congenital anomaly, with a wide range of reported birth prevalence estimates. This quality assurance study describes CHD case ascertainment by the Alberta Congenital Anomalies Surveillance System (ACASS).

Methods: ACASS data for CHD cases were compared with additional sources including the two Pediatric Cardiology clinics in Alberta, the Alberta Children's Hospital Department of Pathology, and hospital records. Cases included live births, stillbirths, and fetal deaths at less than 20 weeks' gestation born in Alberta, Canada, between 1995 and 2002. The birth prevalence of cases and chi-square linear trend analyses were calculated for specific types of heart defects for the total study period.

Results: The ascertainment of CHD cases by ACASS was 45%. The total prevalence of CHD cases was 5.59 per 1000 total births (TBs; 95% confidence interval [CI], 5.32-5.86) when ACASS was the only data source and increased to 12.42 per 1000 TBs (95% CI, 12.03-12.83) when all data sources were used. Although the total prevalence of CHD cases remained stable during 1995 to 2002, the prevalence of atrial septal defect (ASD) and cases with an ASD and ventricular septal defect (VSD) significantly increased. The prevalence of left ventricular outflow tract obstruction cases significantly decreased during the study period.

Conclusions: Pediatric cardiology clinics are worth including as additional ascertainment sources to contribute to more accurate prevalence estimates. The significant increases of ASD and cases with both an ASD and VSD may reflect differences in diagnostic and ascertainment practices.