Waist-Hip Ratio Better Predictor of Seniors' Mortality

Study finds elevated ratio, not body mass index or waist circumference, is appropriate yardstick

13 sept 2009-- In high-functioning older adults, waist-hip ratio is a more accurate predictor of all-cause mortality than either body mass index or waist circumference, according to a study published in the October issue of the Annals of Epidemiology.

Preethi Srikanthan, M.D., of the David Geffen School of Medicine at the University of California in Los Angeles, and colleagues analyzed data from the MacArthur Successful Aging Study on 1,189 community-dwelling older men and women, ages 70 to 79 years at baseline, who met six physical and cognitive criteria for high-function status.

The researchers' unadjusted and adjusted analyses found that an increased waist-hip ratio was associated with increased all-cause mortality, and that the association varied by sex. In women, they observed a graded relationship between waist-hip ratio and mortality (relative hazard, 1.28 per 0.1 increase in waist-hip ratio). In men, they observed a threshold relationship (relative hazard, 1.75 for waist-hip ratio above 1.0 compared to a ratio of 1.0 or below). They found no association between body mass index or waist circumference and all-cause mortality.

"However, given our use of self-reported weight and height data, these findings need to be confirmed in other cohorts of older adults," the authors conclude. "Further research into the mechanisms underlying the increased health risks associated with high waist-hip ratio is also needed, specifically to delineate the role of intra-abdominal visceral fat, relative to pelvic bone size, gluteal muscle, and gluteal fat, in older adults' health risks."

Abstract
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Waist-hip Ratio Better Than BMI For Gauging Obesity In Elderly

Body mass index (BMI) readings may not be the best gauge of obesity in older adults, according to new research from UCLA endocrinologists and geriatricians. Instead, they say, the ratio of waist size to hip size may be a better indicator when it comes to those over 70.

04 sept 2009--In a new study published online in the peer-reviewed journal Annals of Epidemiology, researchers from the David Geffen School of Medicine at UCLA found that the waist-to-hip circumference ratio was a better yardstick for assessing obesity in high-functioning adults between the ages of 70 and 80, presumably because the physical changes that are part of the aging process alter the body proportions on which BMI is based.

"Basically, it isn't BMI that matters in older adults it's waist size," said Dr. Preethi Srikanthan, UCLA assistant professor of endocrinology and the study's lead investigator. "Other studies have suggested that both waist size and BMI matter in young and middle-aged adults and that BMI may not be useful in older adults; this is one of the first studies to show that relative waist size does matter in older adults, even if BMI does not matter."

Using data from the MacArthur Successful Aging Study a longitudinal study of high-functioning men and women between the ages of 70 and 79 researchers examined all-cause mortality risk over 12 years by BMI, waist circumference and waist-hip ratio. They adjusted for gender, race, baseline age and smoking status. The average age of participants was 74.

Obesity is often associated with premature mortality because it leads to an increased risk of diabetes, heart attack, stroke and other major health problems, the study authors say.

The researchers found no association between all-cause mortality and BMI or waist circumference; the link was only with waist-hip ratio. In women, each 0.1 increase in the waist-hip ratio was associated with a 28 percent relative increase in mortality rate (the number of deaths per 100 older adults per year) in the group sampled. Thus, if the waist-hip ratio rose from 0.8 to 0.9 or from 0.9 to 1.0, it would mean a 28 percent relative increase in the death rate. Put another way, if hip size is 40 inches, an increase in waist size from 32 to 36 inches signaled a 28 percent relative death-rate increase.

The relationship was not graded in men. Instead there was a threshold effect: The rate of dying was 75 percent higher in men with a waist-hip ratio greater than 1.0 that is, men whose waists were larger than their hips relative to those with a ratio of 1.0 or lower. There was no such relationship with either waist size or BMI.

The study may have some limitations, the authors noted. For instance, participants' BMI may be underestimated because height and weight were self-reported and older adults tend to report those numbers from their younger, peak years. Also, waist-hip ratios, waist circumference and BMI numbers were based on single measurements, limiting the researchers' ability to gauge how changing body size in old age can affect mortality risk.

Teresa Seeman and Arun S. Karlamangla, both also of UCLA, were co-authors on the study.

The National Institute on Aging funded this research.

The UCLA Division of Geriatrics, within the department of medicine at the David Geffen School of Medicine at UCLA offers comprehensive outpatient and inpatient services at several convenient locations and works closely with other UCLA programs to improve and maintain the quality of life of seniors. UCLA geriatricians are specialists in managing the overall health of people age 65 and older and treating medical disorders that frequently affect the elderly, including falls and immobility, urinary incontinence, memory loss and dementia, arthritis, high blood pressure, heart disease, osteoporosis, and diabetes. UCLA geriatricians can knowledgably consider and address a broad spectrum of health-related factors including medical, psychological and social when treating patients.

Source: University of California, Los Angeles

Waist-Hip Ratio Predicts Risk of Coronary Artery Disease

MANCHESTER, England, Dec. 10 -- A standard measuring tape showing the ratio of fat distribution between the waist and hip can predict coronary artery disease better than body mass index or waist circumference alone, according to investigators here.
Action Points --->
Explain to interested patients that this study suggests that weight reduction that reduces abdominal girth may reduce the risk of cardiovascular events.
Explain to interested patients that BMI, waist circumference, and waist-hip ratio were all associated with increased risk of cardiovascular disease in both men and women.
Men who had the highest waist-hip ratio were 55% more likely to have coronary artery disease than men in the lowest quintile, said Dexter Canoy, M.Phil., M.D., Ph.D., of the University of Manchester, and colleagues, reported online today by Circulation: Journal of the American Heart Association.
For women in the top quintile there was a 91% increase in risk versus women in the lowest fifth, the investigators added.
Waist and hip girths are closely correlated, but both can benefit from weight loss. "Our findings suggested that reducing weight by 1 kg (for a given height) could translate into reducing coronary heart disease risk by 2% in both men and women. Alternatively, reducing waist circumference by 5 cm could lower risk by 11% in men and 15% in women," Dr. Canoy and colleagues wrote.
Those reductions in weight and girth "are achievable with dietary restriction and low-intensity walking three times per week."
Dr. Canoy said that although waist circumference by itself was a reliable marker for heart disease, "risk estimates for waist circumference without hip circumference were lower by 10% to 18%."
Dr. Canoy wrote that BMI, waist circumference, and waist-hip ratio were all "directly related to the development of coronary heart disease, but the magnitude and shape of the associations were influenced by adjustments for possible mediating biological factors and potential confounders."
But "regardless of the model used, waist-hip ratio was independently more consistently predictive of coronary heart disease than waist circumference or body mass index in both men and women," they wrote.
Even among lean individuals, defined as those with a BMI of less than 25 kg/m2 , those with higher waist-hip ratio had about a 50% higher risk than those with lower waist-hip ratios, they wrote.
The waist-hip ratio, he said, was a simple tool to assess body fat distribution.
The finding emerged from the EPIC-Norfolk (European Prospective Investigation Into Cancer and Nutrition in Norfolk) study, a population-based prospective study, which followed 24,508 men and women for a mean of 9.1 years. The mean age of the participants was 60 and all were recruited from general practices in Norfolk, England, from 1993 through 1997.
Twelve percent of men and 11.2% of the women were current smokers and 55.3% of the men were former smokers, as were 32.5% of the women. About 30% of the sample said they had a sedentary lifestyle. The mean BMI was 26.6 kg/m2 for men and for women it was 26.3 kg/m2 .
Waist and hip were measured at enrollment using a standard measuring tape. In addition, the researchers obtained baseline BMI, blood pressure, and serum lipids. Participants also completed a standard questionnaire that assessed medical history, exercise, smoking, and alcohol use.
During follow-up there were 2,600 coronary disease events (1,708 in men), including 662 fatal and 1,938 nonfatal events.
Dr. Canoy said that variation in risks associated with distribution might "reflect differences in metabolic characteristics between abdominal fat and peripheral body fat. Increased abdominal obesity could indicate increased visceral fat accumulation, which is associated with elevated lipolysis, and portal fatty acid efflux, thereby promoting an atherogenic lipid profile, decreasing hepatic clearance of insulin, and increasing peripheral hyperinsulinemia."
Dr. Canoy said more accurate measures of fat distribution may be needed to improve risk assessment in specific subgroups.
The EPIC-Norfolk study is supported by Cancer Research U.K. and the Medical Research Council, with additional support from the Stroke Association, British Heart Foundation, Department of Health, Europe Against Cancer Program, Commission of the European Union, Food Standards Agency, and Wellcome Trust.
Dr. Canoy was supported by the Cambridge Commonwealth Trust/Cambridge Overseas Trust, and Christ's College.
Primary source: Circulation: Journal of the American Heart AssociationSource reference:Canoy D, et al "Body fat distribution and risk of coronary heart disease in men and women in the European Prospective Investigation into Cancer and Nutrition in Norfolk cohort: a population-based prospective study" Circulation 2007; DOI: 10.1161/CIRCULATIONAHA.106.673756.