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Some MI risk factors more hazardous to women than to men

Diabetes, smoking and hypertension more strongly associated with MI in women than in men

Louise Prime

Thursday, 08 November 2018

Several risk factors were more strongly associated with myocardial infarction (MI) in women than in men, research from the University of Oxford has shown. The prospective UK-population-based study, published today in the BMJ, found that sex-specific associations between risk factors and MI declined with age, but, where it occurred, the higher relative risk in women remained.

The researchers analysed data from the UK Biobank to investigate the sex differences in risk factors for MI and how these might vary with age, following 471,998 participants (56% women; mean age 56.2), with no history of cardiovascular disease, for a mean of seven years. During this time, 5,081 participants (1463 (28.8%) of whom were women) had MI – an incidence of 7.76 per 10,000 person-years for women and 24.35 for men.

They reported that higher blood pressure indices, smoking intensity, body mass index, and the presence of diabetes were each 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 statistically significantly higher hazard ratios for MI compared with men: ratio of hazard ratios 1.09 for systolic blood pressure, 1.55 for current smoking, 2.91 for type 1 diabetes, and 1.47 for type 2 diabetes.

The study authors noted: “Although the sex-specific associations between these risk factors and MI attenuated with age, the excess relative risk of MI in women did not.” They also pointed out that the incidence of MI was higher in men than in women for all risk factors except for diabetes.

They said their results suggest that doctors should be vigilant when their female patients are elderly, smoke, have diabetes, or have high blood pressure – and also “highlight the importance of equitable access to guideline-based treatments for diabetes and hypertension, and to weight loss and smoking cessation programmes for women and men in middle and older age”.

They concluded: “Despite the rate of MI being higher in men than women, hypertension, smoking (especially higher intensity), and type 1 and 2 diabetes confer a greater excess risk of MI in women than in men. This excess risk does not attenuate with age. In addition, a rising prevalence of lifestyle associated risk factors, coupled with the ageing population, is likely to result in women having a more similar overall rate of MI to men in the future, with a major additional burden on society and health resources.”

* Millett ERC, Peters SAE, Woodward M. Sex differences in risk factors for myocardial infarction: cohort study of UK Biobank participants. BMJ 2018; 363: k4247.

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