Changes in certification of diabetes with cardiovascular diseases increased reported diabetes mortality in Australia and the United States

Objective: This paper seeks to better understand diabetes-related mortality in Australia and the United States through analysis of the impact of certification practices of diabetes as a multiple cause of death, specifically with cardiovascular diseases (CVDs). Study Design and Setting: Vital registration multiple cause of death data in Australia and the United States since 1999 are used to examine trends in the ratio of diabetes reported in Part I (underlying cause) and Part II (associated cause) of the death certificate, when CVDs are also reported. Results: Underlying cause of death (UCOD) statistics mask the magnitude of diabetes-related mortality. In both countries, since 1999 there has been an increase in the ratio of diabetes deaths in Part I vs. Part II where CVD deaths, including ischemic heart disease and cerebrovascular diseases, are also reported. In Australia, diabetes reported as an UCOD would be 12% lower in 2006 if the ratio from 1999 was applied. Conclusion: The increasing likelihood of physicians to report diabetes in Part I reflects the subjectivity of diabetes death certification. There is a need for specific guidelines on death certification of diabetes with cardiovascular conditions, relating to its reporting as an underlying or associated cause.