Upper-Arm Girth Plus BMI May Sharpen HF Risk Prediction

Pam Harrison

February 17, 2016

SAGAMIHARA, JAPAN — Circumference of the arm at the biceps, an easily measured proxy for lean body mass, adds to body-mass index (BMI) for risk stratification of patients with heart failure, although the same cannot be said for abdominal girth, according to a retrospective cohort study in Japan[1].

"Mid–upper-arm circumference [MUAC], but not waist circumference, showed complementary prognostic predictive capability to BMI in heart-failure patients," write the authors, led by Dr Kentaro Kamiya (Kitasato University Hospital, Sagamihara, Japan).

The findings suggest that MUAC, "which is an inexpensive and easily measurable metric, can be used as a risk-stratification tool over BMI for HF patients . . . and indicate that muscle rather than fat mass is an important complementary prognostic factor for BMI in HF patients."

The study was published February 10, 2016 in JACC: Heart Failure.

An accompanying editorial points out that the so-called obesity paradox in such patients, referring to observations that overweight and obese patients with heart failure and other cardiovascular disease can have better short- and medium-term prognoses than their leaner counterparts, generally refers to BMI as the measure of obesity[2]. But BMI encompasses both lean and fat body mass, which affects its ability to predict risk, according to the editorialists, led by Dr Carl Lavie (Ochsner Clinic, New Orleans, LA).

"The fact that higher values for MUAC portend a better survival in this Japanese HF population supports the premise that muscle mass and muscular strength appear to be protective in HF," they write.

"This was not a large study, and it was from Japan, where body habitus is quite different from the US, so I doubt that MUAC will become a standard measurement anytime soon," Lavie told heartwire from Medscape in an email.

"Still, I believe the most important message from this paper is that more muscle as reflected by higher arm girth suggests a better HF prognosis along with BMI," he said. "This will lead me to emphasize further to my HF patients to try to increase muscle mass and strength."

And yes, it is possible to get even frail HF patients to "bulk up" in response to resistance training, he said. "Heart-failure patients respond to exercise training as per HF-ACTION, which is why Medicare and insurances are paying for cardiac rehabilitation in chronic systolic HF," observed Lavie.

The current analysis included 570 patients discharged from a single center after hospitalization for acute heart failure, who had a BMI of 18.5 kg/m2 or higher; on average, their age was 67, their BMI was 23.2 kg/m2, their waist circumference was 86 cm, and their MUAC was 25.0 cm. Seventy patients died over a median of 1.5 years.

All three metrics—BMI, waist circumference, and MUAC—were significant inverse predictors of mortality after adjustment for potential confounders that included exercise capacity and Seattle Heart Failure Score (SHFS).

Hazard Ratio (HR) for Mortality per Standard-Deviation Increase in Body Metrics

Metric HR (95% CI) P
BMI 0.68 (0.49–0.93) 0.016
Waist circumference
0.76 (0.58–0.99) 0.044
MUAC 0.52 (0.39–0.72) <0.001
*Adjusted for Seattle Heart Failure Score, estimated glomerular filtration rate (eGFR), natriuretic peptides, and 6-minute-walk distance

Prognosis was similarly poor for patients with low BMI and larger waist circumference and those with low BMI and smaller waist circumference (P=0.006 and P<0.001, respectively), compared with those in which both measures were increased.

Patients with low BMI and smaller MUAC (P<0.001), but not those with low BMI and larger MUAC (P=0.829), showed a significantly reduced prognosis compared with patients with increased BMI and MUAC.

The combination of MUAC and BMI (P=0.012) but not BMI plus waist circumference (P=0.763) significantly increased the area under the curve (AUC) on receiver-operator characteristic curve analysis—indicating that MUAC and BMI, but not waist circumference and BMI, were complementary as mortality predictors.

Lavie observed that patients with heart failure as well as the healthy elderly respond well to resistance training, "with increases in muscle mass and muscular strength. In fact, for many very weak and deconditioned HF patients and the elderly, starting with resistance training often helps them to be able to do aerobic training more easily later on."

The study was supported by a "grant for clinical and epidemiologic research of the joint project of the Japan Heart Foundation and the Japanese Society of Cardiovascular Disease Prevention, sponsored by AstraZeneca." Kamiya et al report they have no relevant financial relationships. Lavie "is the author of The Obesity Paradox and has lectured on physical activity, exercise, fitness, and obesity for the Coca-Cola Company." The editorial's coauthors had no relevant financial relationships.

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