ASSESSMENT OF SURVEILLANCE AND VITAL STATISTICS DATA FOR MONITORING ABORTION MORTALITY, UNITED STATES, 1972–1975

To assess the usefulness of vital statistics and surveillance for monitoring abortion mortality, the authors compared data from two systems of classification: 1) deaths classified according to the underlying cause by the National Center for Health Statistics (NCHS) under the International Classification of Disease, Adapted (ICDA) code numbers 640-645 (abortion) for 1972-1975; and 2) abortion-related deaths reported to the Center for Disease Control (CDC) through its epidemiologic surveillance of abortion mortality for the same years. Vital statistics classifications dealing with the underlying cause of death are based on criteria defined by ICDA guidelines applied to all available information listed on death certificates, and exclude some deaths classified as abortion-related by CDC. Surveillance classifications are based on broader criteria developed by CDC for expanded data gathered by individual case investigation. Results showed that the surveillance techniques had identified more deaths as abortion-related and had resolved more cases into the specific abortion categories of legal, illegal, and spontaneous than vital statistics tabulations based on death certificates. The authors estimate that the surveillance system alone reported 88% of all abortion-related deaths, the vital statistics system 52%, and the two systems combined a total of 94%. Inadequate physician documentation on the death certificate was the primary reason vital statistics data contained a smaller number of reported abortion deaths than surveillance data.The National Vital Statistics System coordinated by the National Center for Health Statistics (NCHS) classifies the underlying cause of death according to criteria defined by International Classification of Diseases Adapted (ICDA). The Center for Disease Control's (CDC) epidemiologic surveillance of abortion uses broader criteria developed from expanded data gathered from individual case investigation. By employing these broader criteria, CDC was able to identify more deaths as abortion-related and resolved more cases into the specific abortion categories of legal, illegal, and spontaneous than vital statistics tabulations based on death certificates. In the estimation of the authors, the CDC's surveillance system alone reported 88% of all abortion-related deaths, the vital statistics system 52%, and the 2 systems combined a total of 94%. The authors believe that incomplete death certificate documentation by physicians was the reason for: 2) the discrepancy between NCHS vital statistics and the CDC's, and 2) why deaths correctly attributed to abortion by NCHS were not more specifically classified by type of abortion.