Leading causes of death in England and Wales--how should we group causes?

This article examines how best to identify the leading causes of mortality in England an Wales, by using different way of grouping causes of death, based on a list developed by the World Health Organization (WHO). Four different versions of this list are compared. The leading cause of death across all age groups depends on the ways in which common diseases and external causes are aggregated or disaggregated into groups. Areas of particular debate, examined in this article, are the grouping or splitting of accidents by mechanism and cancers by site within leading cause lists. These affect which causes appear in the top ten, and their order in different age groups.