Waist-calf circumference ratio shows potential as indicator of mortality in older adults

Key takeaways:

• A greater waist-calf circumference ratio was associated with an increased risk for all-cause and cause-specific mortality.
• Researchers believe WCR may outperform BMI in this regard.

A metric that combines measurements of central obesity and muscle mass — called the waist-calf circumference ratio, or WCR — predicted older adults’ risk for mortality from all causes, CVD and other specific causes, a study showed.

Researchers have been searching for ways to replace BMI and waist circumference as indicators of obesity because they cannot differentiate between fat and muscle mass, thus providing new means to predict health outcomes.

Miao Dai, from the department of geriatrics at Jiujiang First People’s Hospital in China, and colleagues wrote in BMC Public Health that whereas WCR was thought to be a better predictor of health outcomes vs. BMI, calf circumference (CC) or waist circumference (WC) alone, “no studies have investigated the association between WCR and mortality risk among older adults.”

The researchers investigated associations between all-cause and cause-specific mortality and all four anthropometric measures in 4,627 older adults enrolled in the 2014 Chinese Longitudinal Healthy Longevity Survey. Participants had a mean age of 84 years, and 1,671 deaths were identified over a median follow-up of 3.5 years.

Dai and colleagues found that compared with the second quartile of WCR, the highest quartile had a greater risk for mortality from:

• all causes (HR = 1.42; 95% CI 1.24-1.64);
• CVD (HR = 1.88; 95% CI, 1.38-2.56); and
• other causes (HR = 1.37; 95% CI, 1.15-1.63).

The HR for cancer mortality was 2.19 (95% CI, 1-4.79) for the first quartile of WCR and 2.69 (95% CI, 1.23-5.89) for the fourth quartile.

The highest CC quartile was linked to a lower risk for cancer mortality (HR = 0.71; 95% CI, 0.55-0.91), and the lowest quartile possessed a greater risk for mortality from CVD (HR = 1.69; 95% CI 1.27-2.25) and other causes (HR = 1.46; 95% CI 1.24-1.73).

Additionally, the lowest quartile of BMI was associated with a higher risk of all-cause (HR = 1.15, 95% CI, 1.01-1.31) and respiratory disease (HR = 1.56; 95% CI, 1.02-2.38) mortality.

Ultimately, “WCR may outperform WC or BMI as a predictor of both all-cause and cause-specific mortality,” the researchers wrote.

They added WCR could indicate lower muscle mass, which, “in turn, is associated with a higher risk of functional decline, disability, worse metabolic health and mortality.”

“Thus, we speculate that the combination of a higher WC and a lower CC, as reflected by a higher WCR, may have an impact on mortality by the cumulative effects of various pathophysiological processes,” they wrote.

Dai and colleagues pointed out such findings were consistent with previous research on BMI associations and continues “the controversy surrounding the ‘obesity paradox.’”

“Thus, until conclusive answers are obtained, it is important to consider the potential benefits and drawbacks of weight loss in older adults, including improvements in morbidity and quality of life as well as potential adverse effects,” they wrote.