Abdominal obesity and the risk of all-cause, cardiovascular, and cancer mortality: sixteen years of follow-up in US women.

Description

In order to evaluate the relationship between abdominal obesity and risk of all-cause, cardiovascular, and cancer mortality in women, Zhang et al. followed 44,636 women of the Nurses’ Health Study for an average of 16 years. Over the follow-up, 3,507 women died. Among them, 751 died from cardiovascular disease (CVD) and 1,748 deaths from cancer were reported. Compared to women with a waist circumference lower than 28 inches, those with a waist circumference equal to or above 88.9 cm (35 inches) had a relative mortality risk of 1.71 (95% CI, 1.47-1.98) after adjusting for potential confounders such as age, physical activity levels, and body mass index (BMI). When a similar model was used, the relative CVD mortality risk was 1.99 (95% CI, 1.44-2.73) and 1.63 (95% CI, 1.32-2.01) for cancer mortality. Comparable associations were observed when waist-to-hip ratio replaced waist circumference as the measure of abdominal obesity. At any given BMI category, women with an increased waistline were at increased risk for all-cause mortality, CVD, and cancer. Interestingly, they found that compared to women with a hip circumference equal to or below 91.4 cm (36 inches), those with a hip circumference equal to or above 114.3 cm (45 inches) had a relative CVD mortality risk of 0.62 (95% CI, 0.44-0.88), even after adjusting for potential confounders such as BMI and waist circumference. This underlines the importance of body fat distribution as a potential confounder of the relationship between excess body weight and mortality. This paper was accompanied by an editorial by Cameron and Zimmet (Circulation 2008;117:1624-6) who, based on the results of Zhang et al. and on other large prospective studies conducted on the topic, stressed that abdominal obesity should be estimated via waist circumference everywhere in the world (with a standardized protocol). They also stated that the paper sends a clear message to the medical community that healthy habits should be encouraged to prevent abdominal obesity-related outcomes such as type 2 diabetes and CVD.