According to research published in The Journal of the American Heart Association, the size of a woman’s hips and waist may be the best indicators of her risk of a heart attack. The study looked at body fat distribution in both men and women and found that waist-to-hip ratio was more strongly associated with risk of myocardial infarction (MI) than was body mass index (BMI) in both genders, especially in women.
The researchers used the UK Biobank database and included 265,988 women and 213,622 men without a history of cardiovascular disease at baseline. All participants were aged 40 to 69 years. The participants completed questionnaires on their lifestyle, environment and medical history, had physical and functional measures performed and provided samples of blood, urine, and saliva. Adiposity was calculated by measuring waist circumference, hip circumference, and height and those data were used to determine BMI, waist-to-hip ratio, and waist-to-height ratio.
Mean BMI was 27 kg/m2 in women and 28 kg/m2 in men. Mean waist circumference, waist-to-hip ratio, and waist-to height ratio were 85 cm, 0.82, and 0.52 in women, respectively, and 97 cm, 0.93 and 0.55 in men, respectively. During mean follow-up of 7 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 a hazard ratio (HR) for MI of 1.22 (1.17; 1.28) in women and 1.28 (1.23; 1.32) in men. A 1-SD higher waist circumference was more strongly associated with risk of MI in women (HR = 1.35 [1.28; 142]) than in men (HR=1.28[1.23; 1.33]). For waist-to-hip ratio, women had a HR of MI of 1.49 (1.39; 1.59) versus 1.36 (1.30; 1.43) in men. The waist-to-height ratio and risk of MI was similar in women and men; the HR was 1.34(1.26; 1.40) in women and 1.33 (1.28, 1.38) in men. In women, higher values of central adiposity, as gleaned from waist circumference, waist-to-hip ratio, and waist-to-height ratio, were associated with a 10% to 20% greater risk of MI than were higher values of BMI. Of these, waist-to-hip ratio was most strongly associated with MI. The strength of association was similar in men but smaller.
The authors noted a few strengths and limitations of the study. They believe the prospective design, large sample size and direct measurement of general and central adiposity on all participants is a strength. However, the population was fairly homogenous in that many participants were white, so further analysis is needed to see if the findings are replicable in a more diverse group. Imaging-derived measurements are also not yet available in the UK Biobank, and the authors believe that combined with the genetic data, these measurements could provide greater insight. While more research is necessary, the authors believe their findings could help physicians identify women at greater risk for MI based on their waist-to-hip ratio.