Barbara Boughton

April 29, 2011

April 29, 2011 (San Diego, California) — Adding omentectomy to Roux-en-Y gastric bypass surgery might help reduce blood glucose levels and improve cholesterol in extremely obese patients, according to research presented here at the American Association of Clinical Endocrinologists (AACE) 20th Annual Meeting and Clinical Congress. But whether these benefits are durable and help stave off conditions associated with obesity, such as diabetes and high cholesterol, remains an open question.

In the randomized controlled trial, 28 obese patients, with body mass index (BMI) of 40 kg/m2 or higher, received either laparoscopic Roux-en-Y gastric bypass surgery alone or Roux-en-Y gastric bypass plus subtotal omentectomy. None of the subjects had comorbid conditions, including diabetes or high cholesterol, at baseline.

Although subjects were well matched for sex, age, and BMI, only those who received omentectomy experienced statistically significant decreases in fasting glucose (P < .05), total cholesterol (P = .004), and very-low-density-lipoprotein cholesterol after 90 days of follow-up. BMI decreased significantly in both groups after 90 days, and the amount of decrease did not differ significantly between the 2 groups.

Those who received omentectomy also experienced a significant improvement in levels of fat-derived hormones, including an increase in the high molecular weight to total adiponectin ratio (P = .013), according to lead author Troy Dillard, MD, a fellow at Oregon Health & Science University in Portland.

"In the context of other studies of longer duration, it should be noted that [omentectomy] is an experimental procedure that in longer-term studies has not been shown to have a durable effect. But it should be noted that this study adds to our understanding of the importance of intraabdominal fat as a significant contributor to cardiometabolic risk," he said.

Inflammatory markers such as tumor necrosis factor-alpha and C-reactive protein were measured in both groups at baseline and follow-up. The blood sugar and cholesterol improvements seen in the omentectomy group could not be explained by changes in these inflammatory markers or BMI alone, since there was little difference between the 2 groups in weight lost or levels of inflammation, Dr. Dillard said.

There were more complications in the omentectomy group — 2 patients developed gastroenterostomy stenosis, which was treated with outpatient endoscopic balloon dilation; in group that received only Roux-en-Y gastric bypass, 1 patient developed urinary retention.

Dr. Dillard noted that the next step in researching the use of omentectomy with weight loss surgery will be to delve into the question of whether removing intraabdominal fat will confer added benefit to those who undergo gastric banding. "Gastric banding still accounts for more than 40% of gastric bypass surgeries in the United States, and we have seen positive results of longer duration [than in this study] when omentectomy is used with gastric banding," he said. "But these positive results do need to be validated in other studies before we can make any broad statement about the clinical utility of omentectomy. We have enough data to suggest there is no long-term benefit to the procedure in patients undergoing Roux-en-Y bypass," he said.

Indeed, the conclusions of this and other studies involving gastric bypass and omentectomy should be interpreted with caution, said Yehuda Handelsman, MD, president of AACE and medical director of the Metabolic Institute of America.

"Roux-en-Y does have a strong effect on glucose issues, but we don't really have enough good long-term data on omentectomy to understand whether it really has additional benefits," he said. "Other studies on omentectomy have shown that it does not result in improvement in insulin resistance," he added.

Dr. Handelsman also noted that the hypothesis that abdominal fat is more important than total body fat in conferring risk for comorbid cardiovascular conditions in obese patients has been challenged in recent research.

Dr. Dillard and Dr. Handelsman have disclosed no relevant financial relationships.

American Association of Clinical Endocrinologists (AACE) 20th Annual Meeting and Clinical Congress: Abstract 801. Presented April 16, 2011.