Diversity in causes of death: A new framework to account for multiple causes of death

Background: The structure of causes of death has changed in low-mortality countries, with recent trends showing increasing cause diversity. However, most research overlooks that several conditions often contribute to the process leading to death. Objective: This paper develops a framework for studying cause-of-death diversity that accounts for multiple causes of death (MCoD). Methods: We introduce novel MCoD life tables to estimate cause diversity based on age-standardized metrics. Two dimensions of diversity are assessed: the average number of causes contributing to death and how diverse these causes are. For the latter dimension, two indexes derived from the Gini–Simpson index are proposed, each based on a different perception of the role of the contributing causes in the process leading to death. All metrics are decomposable and applied to data from Denmark, France, Spain, and the United States. Results: The results show increased cause diversity, both in terms of the average number of causes and how evenly deaths are distributed across groups of causes. MCoD yields higher diversity than the underlying causes of death (UCD), confirming that relying solely on UCD downplays the complexity of the mortality process. However, the increase over time in diversity is more modest when using MCoD compared to UCD. The main driver of increasing cause diversity is the decline in mortality from diseases of the circulatory system. Contribution: This study offers a novel framework for analyzing cause diversity using MCoD. The proposed metrics are intuitive and based on life tables, and provide valuable insights into the growing complexity of the mortality process across countries.