Miriam E Tucker

May 22, 2015

Nashville, Tennessee — Measuring an obese patient's neck may prove to be of greater value than waist circumference in assessing metabolic risk, a new study finds.

The results were presented here at the American Association of Clinical Endocrinologists' 2015 Annual Scientific and Clinical Congress by Zdravko Kamenov, MD, PhD, from Alexandrovska University Hospital, Sofia, Bulgaria.

In the study of 138 obesity-clinic patients, neck circumference cutoffs of 36 cm or greater in females and 39 cm or more in males correlated with criteria for the metabolic syndrome. In women more than men, neck circumference had greater predictive value for some measures than did waist circumference.

"Neck circumference is easily measured and has the advantage of giving additional information in some aspects compared with waist circumference. At this point in time I would not speak about alternative but rather complementary use of both methods to improve the risk evaluation," Dr Kamenov told Medscape Medical News.

"Being an indicator for upper-body subcutaneous fat, which generates the highest amount of free fatty acids, neck circumference may add new information to shape the risk profile of the particular patient," he said, adding that the measure is also a marker and risk factor for obstructive sleep apnea.

Asked to comment, David C Lieb, MD, from Eastern Virginia Medical School, Norfolk, told Medscape Medical News, "I think it's interesting. It's something simple that can be done in clinic."

Dr Lieb added, "I think the waist circumference is something simple that can be done too, but there are drawbacks.…Some people are so obese that the waist circumference can be difficult to do and may be inaccurate. So I like the concept of having something else that may be easy to do in certain patient populations."

It is also interesting that this new work implicates subcutaneous fat as yet another cardiometabolic risk factor, he observed. "When you're thinking about different fat depots, you tend to think of visceral fat around the organs as the 'bad fat.' That's the fat that's really inflammatory. But subcutaneous fat may not be as innocent as we think."

Circumnavigating Cardiometabolic Risk

The 138 study patients were all obese, with a body mass index (BMI) of 30 kg/m2 or higher. Most had prediabetes, 87% had metabolic syndrome (based on international criteria), and 41% had frank diabetes. Nearly a third (30%) were male.

Waist circumference was measured at the midpoint between the inferior costal margin and the superior border of the iliac crest on the midaxillary bone. Neck circumference was measured between the midcervical spine and the midanterior neck just below the laryngeal prominence.

The group had a mean BMI of 35 kg/m2, waist circumference of 108 cm, and neck circumference of 39 cm.

In the women, neck circumference was more strongly correlated than was waist circumference with homeostasis model assessment of insulin resistance (HOMA-IR) (P < .001), as well as with the Finnish Diabetes Risk Score (FINDRISC) score (P < .01) and fasting immunoreactive insulin (IRI) and triglycerides (both P < .05). In fact, there was no correlation with waist circumference for the latter two.

But among the women waist circumference actually correlated better than did neck circumference with BMI and fasting plasma glucose (both P < .001) and also correlated with HbA1c (P < .01), whereas neck circumference did not.

In men, neck circumference also was strongly correlated with HOMA-IR (P < .001) and more so than was waist circumference (P < .05). However, as with the women, waist circumference correlated more strongly than did neck circumference for BMI (P < .001) and was the only one of the two that correlated with fasting plasma glucose (P < .05).

In women, a neck circumference of 34.5 cm or greater had 87% sensitivity for predicting metabolic syndrome, compared with 82% for the waist circumference cutoff of 96.5 cm. In men, waist circumference of 97.0 cm or higher had 98% sensitivity, whereas neck circumference 38.8 cm or above had 93% sensitivity for metabolic syndrome.

Should Both Be Measured?

Although there is a large literature correlating waist circumference with metabolic risk profiles and outcomes — and some of those associations were seen here as well — measuring waist circumference in the clinic has several pitfalls, Dr Kamenov noted.

It can be very difficult to obtain in severely obese people, and if the BMI is greater than 35 kg/m2, waist circumference doesn't add any additional information. And, he added, the measurement suffers from standardization issues and intra- and interoperative variability.

Neck circumference, on the other hand, is much easier to measure and the upper-body subcutaneous fat that it reflects is also a marker for obstructive sleep apnea.

"They measure different things, and for this reason it may be better to measure both to increase the predictive value of the anthropomorphic measure," Dr Kamenov said.

Dr Lieb noted that neck circumference might be an acceptable alternative in patients for whom measuring waist circumference is difficult or who find it uncomfortable.

"I don't know that I would rule out using waist circumference completely. But, there may be certain patients where the neck circumference could replace [the waist] because it's easier or maybe there's added benefit."

However, he cautioned, "Certainly before I would use it in place of other commonly used markers, I would need to see more data."

Dr Kamenov has no disclosures. Dr Lieb has received grant funding from Impeto Medical.

American Association of Clinical Endocrinologists' 2015 Annual Scientific and Clinical Congress. May 15, 2015; Nashville, Tennessee. Abstract 606.


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