LONDON (Reuters Health) – Women are less likely to die from coronary heart disease than men, a well-known finding that is often attributed to the protective effects of oestrogen. However, a report by British investigators suggests that the gender difference is largely the result of environmental factors and therefore not inevitable.
In a study reported in the September 8th issue of the British Medical Journal, Dr. D. A. Lawlor and colleagues, from the University of Bristol, analyzed epidemiologic data from England and Wales and several other countries to investigate the gender-based difference in CHD mortality.
From 1921 to 1949, men and women living in England and Wales exhibited similar patterns of change in CHD mortality rates, and women had consistently lower mortality rates during that period, the authors state.
After 1949, however, mortality rates for men continued to climb, reaching a peak in the early 1970s, while those of women dropped steadily. Similar patterns were noted for men and women living in Australia, France, Sweden, and the United States.
The 20th-century epidemic of CHD was limited to men living in industrialized countries, the authors state. It is unlikely that the cardioprotective effects of oestrogen can explain this finding, because oestrogen levels in women have probably not changed much over the past century and they probably do not vary much between women of different countries.
"These trends indicate that sex differences in mortality from CHD are driven primarily by environmental factors," the investigators note. "Identification of the factors responsible for sex differences in occurrence of coronary heart disease could importantly inform preventive strategies, particularly in countries or parts of countries where rates of CHD are currently increasing."