NASHVILLE, TENN. – Neck circumferences at or above 36 cm in women and 39 cm in men might signal impending metabolic problems, according to researchers from the Medical University of Sofia, Bulgaria.
When patients have necks larger than that, “it is an argument to start more active preventative strategies because they will likely develop metabolic syndrome, if it’s not already present,” said investigator Dr. Zdravko Kamenov, an endocrinologist at the university.
Dr. Zdravko Kamenov
The conclusion is based on a study of waist and neck circumference in 168 obese, hospitalized patients to see which better correlated with metabolic lab values. All the patients had a body mass index above 30 kg/m2; the average BMI was 35. About 70% of the participants were women, and patients with known diabetes, cancer, or chronic kidney or liver disease were excluded from the study.
Waist circumference is well accepted as a marker for abdominal fat and metabolic risk, but it can be difficult to measure and unreliable in obese people, and there are different opinions about where to place the measuring tape. Over the past few years, neck circumference has emerged as an easier alternative and has been associated with metabolic syndrome, obstructive sleep apnea, and heart disease when large.
“At this point, it’s probably better to measure both to increase the predictive value of anthropomorphic measurements,” Dr. Kamenov said at the annual meeting of the American Association of Clinical Endocrinologists.
Measuring both seems best because, in the study, waist circumference correlated better with plasma glucose problems, while neck circumference correlated better with other metabolic issues. Neck circumference also seemed to work better in women than in men, probably because of differences in neck musculature.
For instance, a neck circumference above 35.75 cm was the better predictor of dyslipidemia in women (odds ratio, 4.7; 95% confidence interval, 1.9-12.1,;P = .001). Neck circumference above 34.5 cm in women (OR 5.4; 95% CI 1.80-16.0; P = .003) and 38.75 cm in men (OR 24.6, 95% CI 1.5-398.1, P = 0.024) better predicted metabolic syndrome.
On the other hand, waist circumference over 100.5 cm was more predictive of type 2 diabetes in women (OR 3.2; 95% CI 1.1-9.4; P = .029). Waist circumference above 96.5 cm in women (OR 3.2; 95% CI 1.1-9.5; P = .033) and 101 cm in men was the better predictor of insulin resistance, with a sensitivity of 93% and specificity of 75% in men.
Waist circumference was taken at the midpoint between the inferior costal margin and the superior border of the iliac crest on the mid-axillary line. Neck circumference was measured between the mid-cervical spine and mid-anterior neck just below the laryngeal prominence.
To some extent, neck and waist circumference measure different things. While waist circumference measures visceral fat and to a lesser extent subcutaneous fat, neck circumference is largely a measure of subcutaneous upper body fat, which is important for the generation of the free fatty acids associated with metabolic syndrome, Dr. Kamenov said.
Patients were, on average, 52 years old; 41% turned had type 2 diabetes; 42% had prediabetes; and 87% had metabolic syndrome.
Dr. Kamenov has no disclosures, and there was no outside funding for the work.