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Winter 2009 - Vol.4, No.4 BARIATRIC SURGERY—WHERE DO WE STAND?   Alan M. Brader, M.D. Lancaster General Bariatrics

Table 1

MORTALITY RISK FACTORS IN PATIENTS UNDERGOING GASTRIC BYPASS SURGERY

• Body mass index 50 kg/m2 or greater
• Male gender
• Hypertension
• Known risk factors for pulmonary embolism
  (Previous thromboembolism, preoperative vena cava filter, hypoventilation, pulmonary hypertension)
• Age 45 years or more

The Obesity Surgery Mortality Risk Score (OS-MRS) assigns 1 point to each of these 5 preoperative variables.

Most practitioners, according to their patients, offer little or no guidance for weight management, and many physicians avoid the treatment of obesity. ^{5 6}  Currently, many patients considering weight loss surgery do not discuss it with their primary care giver as a treatment option. Often, a physician learns that one of his or her patient has undergone a weight loss surgery procedure only after the fact.

Who is a Candidate for Weight Loss Surgery?

Any patient with extreme obesity is a potential candidate for weight loss surgery and should be considered, though not all will prove suitable. Unfortunately, only 1% of eligible candidates either seek or are referred for bariatric surgery.

Contraindications to weight loss surgery include a history of cancer undergoing active treatment, a history of severe psychiatric illness or instability, alcohol or drug addiction, severe heart or lung problems, chronic steroid usage, active inflammatory bowel disease, pregnancy, and noncompliance with previous medical care.

Options for Weight Loss Surgery

Health professionals need to have an understanding of the current weight loss procedures to help their patients make informed decisions about all possible treatment options for their illness. For a severely obese individual, surgical therapies currently offer the greatest likelihood for the highest degree of weight loss.

Between 1998 and 2002, there was a 4.5 fold increase in the total number of bariatric operations performed in the United States, ⁸  and the percentage done laparoscopically increased from 2.1% to 17.9% of all cases. During that same 5-year period, the annual rate of open procedures increased only 3 fold. Interestingly, despite the continued rise in the incidence of obesity, the number of total bariatric surgical procedures has now actually decreased slightly from a peak in 2003.

Table 3

 

Results of Surgical Therapy for Obesity

Following weight loss surgery, there are documented reductions in premature death, co-morbidities, and the medical costs of caring for a patient with severe obesity. Two papers published in the New England Journal of Medicine in 2007 demonstrated the beneficial effects of weight loss surgery on mortality.

The Swedish Obesity Study (SOS) was a long-term prospective controlled study of more than 4,000 patients, half of whom had weight loss surgery and the other half of whom had conventional medical therapy. The surgically treated group had a 30% reduction in mortality. Not only was this due to an expected reduction in mortality related to diabetes, but there was also a dramatic decrease in deaths due to cardiovascular disease and cancer. ⁹ 

The second study was a retrospective analysis of 9,949 patients divided equally between surgical and non-surgical weight loss therapy. The surgical group had a 40% reduction in mortality compared with the non-surgical control group. As in the SOS study, there was a 60% reduction in mortality due to cancer and a 92% reduction in death due to diabetes. ¹⁰ 

There are over 35 medical conditions linked to severe or morbid obesity. Multiple studies have demonstrated resolution or improvement of associated co-morbidities following weight loss surgery such as type II diabetes mellitus, obstructive sleep apnea, and hypertension. ^{11  12} 

Since 2001, complication rates associated with weight loss surgery have steadily declined. ¹³  The number of weight loss operations, surgeon experience, and Centers of Excellence have all contributed to better outcomes. In addition, the use of laparoscopy has drastically reduced complication rates compared to similar open procedures.

The ninety day mortality rate for bariatric surgery at Centers of Excellence throughout the United States stands at 0.35%, similar to cholecystectomy. ¹⁴  A prospective study of the perioperative safety of bariatric surgery at ten clinical sites was recently reported in the New England Journal of Medicine. ²  The thirty day mortality rate in 4,776 consecutive patients was 0.3%, and a total of 4.7% patients had at least one adverse outcome. Again, patient characteristics such as extremes of BMI, a history of deep vein thrombosis or pulmonary embolus, obstructive sleep apnea, or impaired functional status correlated with an increased risk of death or complications.

The Metabolic Effects of Weight Loss Surgery

Until recently, white adipose tissue (WAT) was thought to be simply an inert storage depot of fat that lacked any significant metabolic activity. Over the past decade, numerous studies of adipose tissue metabolism have revealed that WAT is actually a major endocrine and secretory organ, responsible for energy homeostasis, immunity function, and many whole body inflammatory conditions. ¹⁴ 

Adipocytes secrete cytokines, termed adipokines, which both regulate incretins (gut hormones) and stimulate many inflammatory mediators in the body. Adipokine secretion can create a chronic sub-inflammatory state in obese individuals which can lead to conditions such as insulin resistance, type II diabetes, non-alcoholic fatty liver disease (NAFLD), dyslipidemia, polycystic ovarian syndrome, hypertension, and metabolic syndrome. ¹⁵  Details about many of these associated conditions in obese patients are discussed in other articles in this symposium.

Perhaps the most dramatic benefit of weight loss surgery besides weight loss is the resolution of type II diabetes mellitus, which is present in nearly 30% of patients who undergo weight loss surgery. Diabetes resolves in 84% to 98% of patients following Roux-en-Y gastric bypass procedures and 48% to 68% after other restrictive procedures. ¹⁶ 

Following a Roux-en-Y gastric bypass, the enteroinsular axis is altered between incretins (gut peptides) and insulin, which results in enhanced insulin sensitivity and secretion. It appears that the exclusion of the upper intestinal tract is the primary mediator of diabetes resolution after Roux-en-Y gastric bypass. ¹⁷  Because of the body’s improvement in insulin response and activity, a physician must adjust a patient’s diabetic regimen significantly to avoid postoperative hypoglycemia.

Bariatric surgery has become an important therapy for patients with BMIs greater than 35 with metabolic syndrome. ¹⁸  In one study of such women who underwent laparoscopic gastric bypass, 89% of patients experienced a resolution of their metabolic syndrome. ¹⁹  A similar study reported a 64% reduction in metabolic syndrome following Roux-en-Y gastric bypass. ²⁰ 

Surgically-induced weight loss also improves nonalcoholic fatty liver disease (NAFLD). A University of Pittsburgh study using pre and post-op liver biopsies in weight loss surgery patients found a reduction in the prevalence of metabolic syndrome from 70% to 14%; in liver steatosis from 88% to 8%; in liver inflammation from 23% to 2%; and in liver fibrosis from 31% to 13%. ²¹  This study demonstrated the relationship between NAFLD and metabolic syndrome in obesity as well as the simultaneous regression of both processes following weight loss surgery.

Lipid profiles also change significantly following Roux-en-Y gastric bypass. ^{22  23}  Two separate studies of patients following laparoscopic Roux-en-Y gastric bypass surgery showed a reduction in the mean total cholesterol, triglyceride, LDL cholesterol, and VLDL cholesterol levels. The total cholesterol/HDL cholesterol risk ratio also dropped and the HDL cholesterol levels rose after surgery. Since obesity and hyperlipidemia are independent risk factors for the development of coronary artery disease, the risk of coronary artery disease can be reduced through weight loss surgery.

The Lancaster General Healthy Weight Management Program

In 2008, the CDC reported a 27.7% prevalence of adult obesity in Pennsylvania. Compared with whites, blacks had a 51% higher prevalence of obesity, and Hispanics had a 21% higher prevalence.

Obesity is currently rampant in Lancaster County. In 2007, the Lancaster General Healthy Weight Management Program was established to help obese patients meet their weight management goals. Surgical and non-surgical options are offered at the 12,500 square foot Healthy Weight Management Center located at 2150 Harrisburg Pike on the Suburban Health Campus.

To date, our comprehensive laparoscopic weight loss surgery program has surgically cared for over 250 patients. The overall program mortality rate is 0.38% (one patient died 16 hours postoperatively from a massive pulmonary embolus). Conversely, over 10% of our patients now enjoy a normal body mass index (BMI 20-25) and 97% of our 12 month gastric bypass patients have lost more than 50% of their excess body weight.

Conclusion

Weight loss surgery has established itself as a proven therapy for the long-term treatment of both severe obesity and its associated co-morbidities. Surgical treatment of severe obesity should be considered by all physicians as a primary mode of therapy for these patients. The physiologic changes associated with severe obesity can be ameliorated or improved after successful weight loss surgery. Potential complications or side effects of weight loss surgery can be minimized at an experienced facility equipped for the care of the severely obese.

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2  Flum DR, et al. Perioperative safety in the longitudinal assessment of bariatric surgery. New England Journal of Medicine 2009 Jul 30;361(5):445-54

3  DeMaria EJ et al. Obesity surgery mortality risk score: proposal for a clinically useful score to predict mortality risk in patients undergoing gastric bypass. Obesity Surgery; 14:134-140.

4  Courcoulas, A. et al. The relationship of surgeon and hospital volume to outcome after gastric bypass surgery in Pennsylvania: a 3-year summary. Surgery 2003 Oct;134(4):613-21.

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6  Frank A. Futility and avoidance: medical professionals in the treatment of obesity JAMA 1993; 269:2132-2133.

7  Dixon J.B. Referral for a bariatric surgical consultation: is it time to set a standard of care. Obesity Surgery 2009 May; 19(5):641-4.

8  Nguyen NT et al. Accelerated growth of bariatric surgery with the introduction of minimally invasive surgery. Archives of Surgery 2005 December; 140:1198-1202.

9  Sjostrom L., et al. Effects of bariatric surgery on mortality in Swedish obese subjects. NEJM 2007; 357: 741-752.

10  Adams TD, et al. Long-term mortality after gastric bypass surgery. NEJM 2007; 357: 753-761.

11  Buchwald H. et al. Bariatric surgery: a systematic review and meta-analysis. JAMA 2004; 292: 1724-37.

12  Maggard MA et al. Meta-analysis: surgical treatment of obesity. Annals of Internal Medicine 2005; 142:547-59.

13  Encinosa WE, et al. Recent improvements in bariatric surgical outcomes. Med Care 2009 May; 47(5): 531-5.

14  Trayhurn, P. Endocrine and signaling role of adipose tissue: new perspectives on fat. Acta Physiol Scand 2005; 184:285-293.

15  Antuna-Puente B. et al. Adipokines: the missing link between insulin resistance and obesity. Diabetes Metabolism 2008 Feb; 34(1):2-11.

16  Vetter ML et al. Narrative review: effect of bariatric surgery on type 2 diabetes mellitus. Ann Intern Med. 2009 January; 150(2):94-103.

17  Rubino, F. et al. The mechanism of diabetes control after gastrointestinal bypass surgery reveals a role of the proximal small intestine in the pathophysiology of type 2 diabetes. Annals of Surgery 2006; 244:741-749.

18  Richardson et al. Metabolic implications of obesity before and after gastric bypass. Gastroenterology Clinics of North America 2005; 34:9-24.

19  Giusti et al. Effect of laparoscopic banding on body composition, metabolic profile and nutritional status in obese women: 12 month follow-up. Obesity Surgery 2004; 14(2):239-45.

20  Batsis et al Effect of bariatric surgery on the metabolic syndrome: a population based, long-term controlled study. Mayo Clin Proc. August 2008; 83(8):897-906.

21  Mattar, S. et al. Surgically-induced weight loss significantly improves nonalcoholic fatty liver disease and the metabolic syndrome. Annals of Surgery 2005 October; 242(4):610-620.

22  Nguyen NT et al. Resolution of hyperlipidemia after laparoscopic Roux en Y gastric bypass. Journal of the American College of Surgeons 2006 July; 203(1):24-29.