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/s eparation records, we compared the the congenital anomalies ascertained by CCASS for the period of January 1, 1990 to December 31, 1993 in the provinc e of Alberta with corresponding figures obtained from Alberta Congenital An omalies Surveillance: System (ACASS), a specific-purpose surveillance progr am collecting information on congenital anomalies from multiple sources wit h mechanisms to evaluate diagnosis. Rates of congenital anomalies estimated by CCASS tended to be higher. Agreement between CCASS and CASS depended on diagnosis: for the International Clearinghouse for Birth Defects Monitorin g System standard categories of congenital anomalies (except for anomalies off abdominal wall), agreement usually exceeded 50%; for less clear-cut dia gnoses, it was well below 50%. We conclude that routine medical records can be used for surveillance purposes for major congenital anomalies with clea r-cut diagnosis.