Congenital anomalies ascertained by two record systems run in parallel in the Canadian Province of Alberta

To assess the quality and appropriateness of Canadian Congenital Anomalies Surveillance System (CCASS), a system based on routine hospital admission/separation records, we compared the congenital anomalies ascertained by CCASS for the period of January 1, 1990 to December 31, 1993 in the province of Alberta with corresponding figures obtained from Alberta Congenital Anomalies Surveillance System (ACASS), a specific-purpose surveillance program collecting information on congenital anomalies from multiple sources with mechanisms to evaluate diagnosis. Rates of congenital anomalies estimated by CCASS tended to be higher. Agreement between CCASS and ACASS depended on diagnosis: for the International Clearinghouse for Birth Defects Monitoring System standard categories of congenital anomalies (except for anomalies of abdominal wall), agreement usually exceeded 50%; for less clear-cut diagnoses, it was well below 50%. We conclude that routine medical records can be used for surveillance purposes for major congenital anomalies with clear-cut diagnosis.