Central adiposity in older adults tied to higher mortality, heart disease risk
Healthier agers (ie, nonsmokers without disease-related weight loss) with higher central adiposity who are overweight exhibit substantial excess mortality and risk of heart disease, a recent study has found.
“The claimed BMI-defined overweight risk paradox may result in part from failing to account for central adiposity, rather than reflecting a protective physiologic effect of higher body-fat content in later life,” researchers said.
“We also found no evidence of a risk paradox with moderate obesity, but we instead saw overall increases in mortality compared with individuals with a normal BMI and lower waist-to-hip ratio (WHR),” they added.
When WHR was not taken into account, overweight participants showed comparable risk of mortality with normal-weight individuals (hazard ratio [HR], 1.09; 95 percent CI, 0.99 to 1.19; p=0.066). However, mortality was greater among normal-weight participants with a higher WHR (HR, 1.33; 1.08 to 1.65) than those with a lower WHR. [Am J Clin Nutr 2017;106:130-135]
Overweight participants with a higher WHR were likely to have substantial excess mortality (HR, 1.41; 1.25 to 1.61) and greatly increased incidence of coronary artery disease (CAD; sub-HR, 1.64; 1.39 to 1.93) compared with normal-weight individuals with a lower WHR.
“It is clear from our data that higher central adiposity in both the normal BMI range and the combination of overweight and central adiposity should be considered a risk factor for clinical risk assessment and public health purposes in healthy agers,” researchers said.
The joint associations of BMI and WHR tertiles showed no significant interaction (p<0.05) with physical activity, sex, age group (60 to 64 years and 65 to 69 years) or smoking history (never or former smoker) as regards mortality.
“Higher levels of physical activity were an independent protective factor, but we did not find that these negated the effects of overweight or class I obesity,” researchers noted.
These finding suggest that the reported risk paradox of being overweight in older persons (overweight tied to lower mortality) may be attributable to failure to account for central adiposity, which is not measured by BMI.
“Controlling or reducing adiposity to increase the chances of [successful ageing] is of particular relevance to our studied group of healthier agers,” researchers said. “Our findings therefore do not support the theory that the overweight risk paradox in healthy agers is a real protective physiologic effect.” [Int J Obes (Lond) 2015;39:82–4]
In this study, researchers followed a total of 130,473 UK Biobank participants aged 60 to 69 years (baseline 2006 to 2010) for ≤8.3 years (n=2,974 deaths). Current smokers and individuals with recent or disease-associated weight loss (eg, from dementia, heart failure or cancer) were not included, generating a “healthier agers” group.
Survival models were adjusted for age, sex, alcohol intake, smoking history and educational attainment. Population and sex-specific lower and higher WHR tertiles were <0.91 and ≥0.96 for men and <0.79 and ≥0.85 for women, respectively.