Approximately 4 million individuals and 67,000 coronary heart disease events from 86 studies were included in the researcher's meta-analysis. They discovered that in 75 cohorts (total 2-4 million participants) that adjusted for cardiovascular risk factors aside from coronary heart disease, the combined adjusted female-to-male relative risk ratio (RRR) of smoking in comparison with not smoking for coronary heart disease was 1-25 (I.e., 25% higher for women). For each additional year of follow-up RRR increased by 2%, meaning the longer a woman smokes, the risk of developing CHC is higher in comparison with a man that has smoked the equivalent length of time.
According to the authors, cigarette smoking is one of the leading causes of coronary heart disease worldwide, and will remain so as populations that have up to now been somewhat unaffected by the smoking epidemic, begin to smoke to a degree previously observed only in high-income countries. This expectation is particularly true for young women in whom the popularity of smoking, especially in low to middle-income countries, may be on the rise.
The actual RRR may be even higher, say the authors. The average consumption of cigarettes per day is less in women than men, and in several countries the smoking epidemic duration has been a lot shorter in women. Both these factors suggest that the RRR may actually be even higher for women.
The researchers explained,
"The finding that, among smokers, the excess risk of coronary heart disease in women compared with men increases by 2% for every extra year of study follow-up lends support to the idea of a pathophysiological basis for the sex difference.
For example, women might extract a greater quantity of carcinogens and other toxic agents from the same number of cigarettes than men. This occurrence could explain why women who smoke have double the risk of lung cancer compared with their male counterparts."
In a concluding statement the authors say,
"Physicians and health professionals should be encouraged to increase their efforts at promotion of smoking cessation in all individuals. Present trends in female smoking, and this report, suggest that inclusion of a female perspective in tobacco-control policies is crucial."
In an associated comment made by Dr Matthew A Steliga, University of Arkansas for Medical Sciences, Little Rock, AR, USA, and Dr Carolyn M Dresler, Tobacco Prevention and Cessation Program, Arkansas Department of Health, Little Rock, AR, USA said,
"What makes the realization that women are at increased risk worrisome is that the tobacco industry views women as its growth market."
They conclude, that National and international organizations such as the International Network of Women Against Tobacco and the WHOs Tobacco Free Initiative are important reference organizations to promote more effective tobacco cessation in women. Although more men than women smoke, those women who smoke do have a greater risk for having coronary heart disease and therefore targeting of both sexes is imperative for smoking prevention and cessation on a global, national, and individual basis.