Trends in sex differences in mortality from heart disease

Editor—In referring to our paper, Editor's choice of 8 September states that “A group from Bristol grabs attention by arguing that the fact that men have much higher rates of heart disease than women may be nothing to do with gender.”¹,² This shows the current confusion over the use of the words sex and gender.

The Oxford English Dictionary (http://dictionary.oed.com/entrance.dtl) gives the following definition for gender: “Intended to emphasize the social and cultural, as opposed to the biological, distinctions between the sexes.” We would agree with this distinction.

In our study we argued that the fact that men have much higher rates of heart disease than women may be nothing to do with sex—that is, biology such as the female hormone oestrogen—but something to do with gender. Indeed, although the data presented in our study cannot test such a hypothesis, in the discussion we raised the possibility that gender differences in dietary habits (related to social and cultural influences on the way that women prepare, eat, and serve food to themselves and men) may be part of the reason why death rates from heart disease differ between women and men.

After our paper was published we discovered a letter published in the Lancet in 1956 that put forward the same theory.³ The author's suggestion was based on his observations of variations in the sex difference between different ethnic groups in the United States and between different geographical areas.

Our analysis of secular trends over the past century and contemporary geographical variations suggested to us the same likely cause for the emergence of the difference between women and men in the occurrence of coronary heart disease. We were not aware of this letter at the time our paper was published; had we been, we would have cited it.