Stronger association between central adiposity and risk of MI than general adiposity
Sex Differences in the Association Between Measures of General and Central Adiposity and the Risk of Myocardial Infarction: Results From the UK Biobank
Introduction and methods
Body mass index (BMI) is a measure of general adiposity, while waist circumference, waist-to-hip ratio, and waist-to-height ratio, are measures of central adiposity that are more strongly related to CV risk [1,2]. There are important gender differences in body fat distribution, but it is not clear how exactly these differences reflect on CV risk.
In this study, the gender-specific relationship between measures of general and central adiposity and the risk of incident MI was evaluated, in women and men without a prior history of CVD, who were included in the UK Biobank.
The UK Biobank is a large prospective, population-based cohort study, designed to identify associations between baseline characteristics and health outcomes in adults aged 40-69 years [3,4]. For the present analysis, participants with a history of CVD at baseline or with a BMI <15 or >60 kg/m2 were excluded, leaving a sample of 479,610 individuals. The study end point was the incidence of fatal or non-fatal myocardial infarction (MI).
- During a mean follow-up of 7.1 years, 5710 cases of MI (28% women) were recorded, including 1292 (25% women) events that occurred within 2 years of follow-up.
- A 1-SD higher BMI was associated with an HR for MI of 1.22 (95%CI: 1.17-1.28) in women and 1.28 (95%CI: 1.23-1.32) in men (P for interaction=0.15).
- A 1-SD higher waist circumference was more strongly associated with the risk of MI in women than in men, with a marginal statistical significance. The HRs were 1.35 (95%CI: 1.28-1.42) in women and 1.28 (95%CI: 1.23-1.33) in men (P for interaction=0.048). The corresponding women-to-men ratio of HRs was 1.07 (95%CI: 1.00-1.14).
- A 1-SD higher waist-to-hip ratio was associated with an HR of MI of 1.49 (95%CI: 1.39-1.59) in women and 1.36 (95%CI: 1.30-1.43) in men (P for interaction<0.001), with a corresponding women-to-men ratio of HRs of 1.15 (95%CI: 1.06-1.24). The association between a 1-SD higher waist-to-height ratio and the risk of MI was similar between genders. The HRs were 1.34 (95%CI: 1.27-1.40) in women and 1.33 (95%CI: 1.28 1.38) in men (P for interaction=0.38).
- In women, higher values of central adiposity were associated with a 10% to 20% greater risk of MI compared with higher values of BMI. Of these, waist-to-hip ratio was more strongly associated with MI than waist circumference and waist-to-height ratio. In men, waist-to-hip ratio was also significantly more strongly associated with MI compared with BMI.
In a large population-based cohort, the waist-to-hip ratio was more strongly associated with the risk of MI compared with BMI, especially in women. These findings suggest that gender differences in quantity and distribution of adipose tissue may have different implications on the risk of MI.