Objectives: To investigate sex differences in risk factors for incident myocardial infarction (MI) and whether they vary with age.
Participants: 471 998 participants (56% women; mean age 56.2) with no history of cardiovascular disease.
Main outcome measure: Incident (fatal and non-fatal) MI.
Results: 5081 participants (1463 (28.8%) of whom were women) had MI over seven years mean follow-up, resulting in an incidence per 10 000 person years of 7.76 (95% confidence interval 7.37 to 8.16) for women and 24.35 (23.57 to 25.16) for men. Higher blood pressure indices, smoking intensity, body mass index, and the presence of diabetes were associated with an increased risk of MI in men and women, but associations were attenuated with age. In women, systolic blood pressure and hypertension, smoking status and intensity, and diabetes were associated with higher hazard ratios for MI compared with men: ratio of hazard ratios 1.09 (95% confidence interval 1.02 to 1.16) for systolic blood pressure, 1.55 (1.32 to 1.83) for current smoking, 2.91 (1.56 to 5.45) for type 1 diabetes, and 1.47 (1.16 to 1.87) for type 2 diabetes. There was no evidence that any of these ratios of hazard ratios decreased with age (P>0.2). With the exception of type 1 diabetes, the incidence of MI was higher in men than in women for all risk factors.
Conclusions: Although the incidence of MI was higher in men than in women, several risk factors were more strongly associated with MI in women compared with men. Sex specific associations between risk factors and MI declined with age, but, where it occurred, the higher relative risk in women remained. As the population ages and the prevalence of lifestyle associated risk factors increase, the incidence of MI in women will likely become more similar to that in men.
Sex differences in the association between major and modifiable risk factors with cardiovascular disease
Most of the burden of cardiovascular diseases (CVD) is explained by a composite of physiological and lifestyle factors - chiefly, elevated blood pressure, obesity, diabetes, cigarette smoking, poor diet, and physical inactivity. There is increasing evidence that some of these risk factors have stronger effects on CVD in women than men. Although preventive strategies aimed at lowering the burden of these risk factors will benefit all, a sound knowledge of whether there are meaningful sex differences in relationships between traditional chronic disease risk factors and disease outcomes should help promote development of effective, sex-specific interventions. Addressing sex differences in relationships between risk factors and CVD risk is of importance from clinical and public health perspectives. Identifying significant sex differences in how risk factors relate to CVD risk should provide an impetus for targeted interventions aimed at reducing the prevalence of disease. Moreover, sex-specific estimates of disease risks associated with modifiable risk factors are essential for accurate estimation of the burden of disease due to these factors. These findings would help to inform the decision making process to maximize the efficacy of the allocation of health care resources, both in the UK and worldwide. Sex-specific estimates for the association between common lifestyle risk factors (elevated blood pressure, obesity, diabetes, cigarette smoking and a poor diet) and the risk of incident CVD will be determined. These sex-specific estimates will be used to evaluate whether or not the risk of stroke and coronary disease associated with these risk factors is similar between women and men. Analyses will be conducted in all individuals, as well as in subgroups defined by age, so as to identify sex-specific changes with ageing (for example, post-menopause), and socioeconomic status, to explore the effects of deprivation. Baseline and follow-up data on the full cohort of women and men in the UK Biobank, except those with pre-existing CVD at baseline, are requested.
|Lead investigator:||Professor Mark Woodward|
|Lead institution:||George Institute for Global Health|