News Author: Jacquelyn K. Beals, PhD
CME Author: Désirée Lie, MD, MSEd
Medscape Today – Journal 15/10/08
Superobese patients who spend an average of 9 preoperative weeks on a very-low-calorie diet (VLCD) have reduced morbidity and mortality rates associated with bariatric surgery. The weight loss regimen appears to improve factors that influence technical aspects of surgery and reduces patient comorbidities.
George M. Eid, MD, FACS, from the Division of Minimally Invasive Surgery at the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, presented the study here today at the American College of Surgeons 94th Annual Clinical Congress. The study reflected the literature on bariatric surgery that shows superobesity (body mass index [BMI] > 50 kg/m2) to be a major risk factor for adverse outcomes. Other risk factors are male sex, age, lower socioeconomic status, or smoking.
Dr. Eid noted in his presentation that the 30-day mortality rate reported for 575 bariatric surgery patients in the Veterans Administration system is 1.4%, with a 19.7% overall rate of complications. Superobese patients have a 2.3% mortality rate and a 29% morbidity rate.
The surgical risks associated with superobesity are both physiologic and technical. The physiology involves several comorbidities: diabetes mellitus, sleep apnea, congestive heart failure, hypertension, degenerative joint disease, and chronic obstructive pulmonary disease. Technical challenges include excess visceral fat, an enlarged liver (hepatomegaly), and a thickened abdominal wall.
The goal of the present study was to “evaluate changes in obesity-related comorbidities, liver size, and visceral and subcutaneous adipose tissue volumes following preoperative weight loss with a…VLCD program, and relate these changes with postoperative outcomes,” said Dr. Eid.
“The kind of medical weight loss we use in this study is called very-low-calorie diet. This is a mostly high-protein liquid diet with balanced electrolytes,” Dr. Eid told Medscape Surgery. “My understanding is it’s only FDA [US Food and Drug Administration] approved for a 3-month period.”
Even without the US Food and Drug Administration regulation, medical weight loss is rarely successful in the long-term.
“Medical weight loss has a high incidence of failure over the long period of time,” Dr. Eid told Medscape Surgery. “If you follow a patient at 6 and 12 months they regain their weight, and maybe gain more weight….Studies have been done showing over 1 to 2 periods of follow-up in a medical weight loss patient that you have a high percentage of weight regain and going back to square one.”
Data were collected prospectively from 30 consecutive patients (27 men and 3 women) with a BMI of more than 50 kg/m2 who were seen between August 2004 and April 2007 and were invited to take part in a supervised VLCD program. Participants received 5 servings of a high-protein liquid diet totaling 800 calories per day and were seen weekly for medical and behavioral follow-up. The targeted weight loss was 10% of body weight for patients with a BMI between 50 and 55 kg/m2. For patients with a BMI of more than 60 kg/m2, the goal was a BMI of less than 55 kg/m2.
Mean patient age was 53 years (age range, 34 - 65 years), mean baseline BMI was 56 kg/m2 (range, 51 - 69 kg/m2), and average period on the VLCD was 9 weeks (range, 4 - 13 weeks). To assess the physical changes that accompanied weight loss, computed tomographic scans of the abdomen were done at the beginning of the VLCD program and after its completion.
The scans determined liver volume in cubic centimeters, the depth of the abdominal wall in centimeters, and the subcutaneous adipose tissue and visceral adipose tissue in centimeters squared at locations 12 cm and 20 cm from the xiphoid process. The second scan showed significant improvements in BMI, liver volume, depth at 12 cm and 20 cm from the xiphoid process, total subcutaneous adipose tissue at 12 and 20 cm from the xiphoid process, and visceral adipose tissue (each P < .001).
Preoperative weight-loss with VLCD improved poorly controlled diabetes mellitus in 10 (62.5%) of 16 diabetic subjects. It also improved poorly controlled hypertension in 8 (40%) of 20 of affected patients, and improved degenerative joint disease with limited mobility in 12 (57%) of 21 of patients with this problem. “Some even stopped using their wheelchair and were able to do limited activity by walking,” observed Dr. Eid.
No deaths occurred in the patients who experienced weight loss with VLCD before their bariatric surgery, even with 1-year follow-up. There were 2 postoperative complications: a questionable pulmonary embolism that was examined and had a good outcome, and a minor bleeding episode. Historical data from the same institution report 0% mortality and 6.7% morbidity rates. National Veterans Administration data for superobese patients, as noted previously, show 2.3% mortality and 29% morbidity rates.
Dr. Eid and his colleagues conclude that “bariatric surgical outcomes in superobese patients are optimized through preoperative VLCD.” The significant reductions in liver volume, abdominal wall depth, and visceral adipose tissue and subcutaneous adipose tissue (technical factors) improve the surgical procedure. Improvements in diabetes, hypertension, and degenerative joint disease (physiologic factors) enhance the health of the patient.
“I had two factors. I had the technical factors and those had to do with decreasing the amount of fat and the size of the liver so we had better access to our organ and we can do a better job,” Dr. Eid told Medscape Surgery. “But also we had improvement in their medical condition with diabetes and everything, so it’s a two-pronged approach. On the one hand, you improve technical factors, but on the other hand you improve their comorbidities so you have less risk of complication and postoperative problems.”
