Obesity is defined as a disease in which excess fat has accumulated to the point where it may adversely affect health and increase mortality. In the U.S., the prevalence of obesity is currently 28%, with much higher rates in certain regions and among specific ethnic groups (National Institutes of Health, 2001). While Canada hasn't quite caught up with its neighbour to the south, surveillance data of Canadians > 20 years of age shows a marked rise in obesity (body mass index [BMI] > 30 kg/m2) over recent years, and there's no evidence that this trend is about to level off. Indeed, the World Health Organization has recognized an epidemic of obesity throughout most of the developed and developing world. Especially alarming is the increasing prevalence of obesity in children, as it heralds a lifelong disorder with great risk of related disease.

Morbid obesity is defined as a chronic disease in which excess adipose tissue results in a BMI > 40 kg/m2, and is often associated with several comorbidities. In addition, it impacts on the activities of daily living such as tying shoes, hygiene - e.g. the ability to wipe oneself after a bowel movement - or fitting into a car, bus or plane seat. Morbidly obese individuals also suffer from social stigmatization and discrimination.

Obesity can be treated, however, and research has shown that the weight loss following bariatric surgery significantly reduces comorbidities such as diabetes, high blood pressure and sleep apnea - by up to 70%.

What are the treatment options for morbid obesity?
There are a variety of medical treatments available, including:

• diet therapy
• physical activity
• behaviour therapy
• pharmacotherapy

The specifics of these treatments aren't the subject of this article, but it's important to note that medical management of morbid obesity is unfortunately not often successful. Fewer than 10% of morbidly obese patients who manage to reduce their weight using a combination of diet, behaviour therapy and exercise, can maintain this weight loss for more than 1 year.

Another option for these people is bariatric surgery, i.e. the treatment of severe obesity through surgery. This field has continually evolved since its initial sporadic and tentative introduction in the 1950s. Today, there are a number of different approaches to choose from that fall into three categories: restrictive, malabsorptive and a combination of the two. In regard to the question of when bariatric surgery is indicated, the National Institutes of Health Consensus Conference in 1991 concluded the following:1 - medical therapies generally fail to control severe obesity - surgery should be considered for individuals with BMI > 40 kg/m2 - when comorbidities such as diabetes or sleep apnea are present, consider surgery starting at BMI > 35 kg/m2. While patients can lose up to 25 kg over 12 months with medical therapy, almost all will regain this weight - and more - in the subsequent 5 years. Some repeat this cycle several times, at which point they get so frustrated and incapacitated by their weight that they seek surgical therapy. See Table 1 for a comparison of risks and long-term outcomes of the most common bariatric surgical procedures.

Does bariatric surgery produce sustained weight loss?
Several key studies have demonstrated long-term weight loss with bariatric surgery. The Swedish Obese Subjects (SOS) study, comparing 2,000 obese people treated with either bariatric surgery or conventional medical means, reported sustained weight changes of 14-25% after 10 years.2 Scopi­naro and colleagues found average excess weight loss to be 74% at 10 years after biliopancreatic diversion (BPD).3 Fobi et al, using the transected banded gastric bypass technique, reported 68% excess weight loss after more than 10 years.4 Our own data, comprised of patients who've been followed up for > 10 years, show excess weight loss > 67%, similar to the 67% Biron and colleagues found for biliopancreatic diversion with duodenal switch (BPD/DS).5

Is comorbidity improved?
The sustained weight loss produced by bariatric surgery does indeed serve to improve or cure the comorbidity associated with obesity. In 2004, Buchwald et al conducted a meta-analysis of 22,094 morbidly obese individuals who had weight loss surgery.6 They compared 3 different kinds of procedures: restrictive (adjustable band and gastroplasty), malabsorptive (BPD/DS), and a combination thereof (Roux-en-Y gastric bypass). Excess weight loss varied between 48% and 70%. Diabetes resolved completely in 77% of patients, hyperlipidemia improved in 70%, and high blood pressure was cured in 62%. Obstructive sleep apnea got better in more than 80% of study subjects. Our own data also show reductions in physician and hospital visits for common diseases such as cancer, infections, musculoskeletal disorders and cardiovascular disease after people lost weight through bariatric surgery.

What are the pros & cons of the different approaches?
Vertical banded gastroplasty (VBG) VBG is a purely restrictive procedure (see Figure 1) with no malabsorption component and no dumping. Dumping syndrome refers to rapid gastric emptying of undigested stomach contents into the small intestine, in people who've had surgical gastric bypass. The main symptoms are abdominal cramps, nausea and vomiting. Anemia is rare in VBG and vitamin B12 deficiency is almost unknown. Patients have to be very careful to chew their food completely to avoid vomiting. Although sodas and ice cream go down pretty well, they should still be avoided because of the high calorie content.

Complications of VBG include leakage, stenosis with persistent vomiting, ulcera­tion, wound infection and incisional hernia (in the open cases), as well as band erosion with life-threatening gastrointestinal bleeding. Perioperative mortality is approximately 0.1-0.5% and excess weight loss after 5 years averages ~50%. The procedure isn't used in North America and is being supplanted in Europe and elsewhere by laparoscopic adjustable gastric banding (LAGB).

Laparoscopic adjustable gastric banding (LAGB)
Adjustable gastric banding was popularized by Dr. Lubomyr Kuzmak, who devised a band with an inflatable balloon as the lining (Figure 2). This balloon is connected to a small reservoir placed under the skin of the abdomen; with this, the balloon may be inflated (thus reducing the size of the stoma) or deflated (enlarging the stoma). Adjustable bands can now be inserted laparoscopically, saving the patient the discomfort and complications of a large incision. There's no anemia, dumping or malabsorption, but the disadvantages include the need for strict adherence to diet­ary guidelines. Since patients don't always follow these guidelines, the rate of unacceptable weight loss (i.e. insufficient weight loss, from the patient's perspective) is > 30%.

Complications include band slippage, band erosion and port infection or deflation/leakage. Overall, this is a safe operation, however, with mortality rates of ~0.01- 0.05%. The expected weight loss with this procedure is 0.5-1 kg per week, amounting to excess weight loss at 5 years of ~ 50%.

Laparoscopic sleeve gastrectomy (LSG)
In this approach, up to 80% of the stomach is resected. LSG has been used as a first-stage baria­tric procedure to reduce surgical risk in very heavy patients (> 200 kg). Indeed, this may be the procedure's most useful application at the present time. The mechanism of weight loss and resultant comorbidity improvement may be related to a reduction of the eating capacity, or it may have to do with neuro­humoral changes following the removal of most of the stomach. Alternatively, it may be the result of some other, unidentified factor(s). If weight loss stops before the targeted goal is achieved, LSG can be converted to biliopancreatic diversion with duodenal switch or to gastric bypass. LSG alone doesn't create malabsorption.

Biliopancreatic diversion (BPD)
This procedure involves a limited gastrectomy and attachment of the lower 200-cm segment of the small intestine to the remaining stomach pouch, creating an alimentary limb (Figure 3). The long remaining biliopancreatic limb is connected to the lower part of the alimentary limb, leaving a common channel 50-75 cm in length. The approach creates significant malabsorption, which acts to maintain weight loss in the long run.

From the patient's perspective, the great advantage of this operation is the ability to eat large quantities of food while achieving long-term weight loss. Disadvantages are the association with loose stools, stomal ulcers and foul-smelling stools and flatus. The most serious complication is protein malnutrition - which can cause hypoalbuminemia, anemia, edema, asthenia and alopecia - and generally requires hospitalization and 2-3 weeks of hyperalimentation. BPD patients need to take supplemental calcium and vitamins, particularly vitamin D, for the rest of their lives. Because of the potential for significant complications, they require lifelong follow-up.

Biliopancreatic diversion with duodenal switch (BPD/DS)
This approach combines a 70-80% gas­trectomy, reducing the stomach along the greater curvature (sleeve gastrectomy), with a duodenal switch - the lower part of the small intestine is connected to the beginning of the duodenum rather than directly to the stomach (Figure 4). Continuity of the gastric lesser curve is thus maintained while the stomach volume is reduced. The efferent limb acts to decrease overall caloric absorption and creates a long biliopancreatic limb diverting bile from the alimentary contents, specifically to induce fat malabsorption. As with BPD, the biliopancreatic limb is reattached to the lower part of the alimentary limb. The BPD/DS procedure minimizes stomal ulcer and dumping syndrome.

BPD and its variants are complex procedures, and prospective patients who wish to consider BPD/DS should seek out experienced surgeons with lifelong follow-up programs. Mortality is ~1% in the best centres, and excess weight loss of > 67% after 10 years has been reported.

Roux-en-Y gastric bypass
The Roux-en-Y gastric bypass was developed by Dr. Edward E. Mason of the University of Iowa, and is based on his observation that women who had undergone partial gastrectomy for peptic ulcer disease tended to remain underweight after the surgery. Subsequent modifications to the procedure have included use of the Roux-en-Y technique to avoid loop gastroenterostomy and the bile reflux that may ensue (Figure 5). As well, the Roux limb has been lengthened to 100-150 cm, which has served to shorten the common limb to 200-250 cm, achieving a greater element of malabsorption and improved weight loss. The gastric bypass differs from the BPD in that the size of the gastric pouch is smaller (10-15 mL vs 100-200 mL) and that the common channel is longer (~250 cm vs 75 cm). Finally, the use of retrocolic and retrogastric routing of the gastrojejunostomy eases the technical difficulties of the procedure and improves long-term weight management results.

Complications include leaks at the junction of the stomach and small intestine (anastomotic leaks) and late complications such as narrowing of the stoma, anemia and vitamin B12 deficiency. Since the food stream bypasses the duodenum, the primary site of calcium absorption, the possibility of calcium deficiency exists, and all patients should take supplemental calcium to forestall this.

Dumping syndrome can occur when the patient eats refined sugar - symptoms include rapid heartbeat, nausea, tremor and feeling faint, sometimes followed by diarrhea. Since no one likes these kinds of sensations, people who've undergone gastric bypass surgery tend to avoid sweets, a circumstance that further helps them in their efforts to lose weight.

Does bariatric surgery reduce mortality?
Numerous studies have found a decreased mortality risk in individuals who have lost weight after bariatric surgery. We reported for the first time in 2004 that permanent weight loss reduced the relative risk (RR) of death by 89% compared to no surgery.7 In this study, we followed 1,035 of our patients after bariatric surgery at the McGill University Health Centre (MUHC). We compared their outcomes to a control group of 5,746 individuals who didn't have weight loss surgery (and thus stayed morbidly obese). The absolute mortality rate during the 5-year follow-up was 0.7% in the bariatric surgery group compared with 6.2% in controls.

The SOS study showed similar results; the surgery group had a risk of death that was reduced by 20-30% thanks to fewer heart attacks and cancers.2 A study from Australia, looking at laparoscopic adjustable gastric banding, found a 72% lower hazard of death in the treated patients compared to controls.8 Researchers from the University of Padua, Italy, also evaluated long-term data from obese patients who had undergone adjustable gastric banding - and report a 62% reduction in the RR of death in the surgery group.9 Concentrating on gastric bypass surgery, a collaborative research project conducted in Utah found a 40% reduction in mortality in treated subjects, with fewer deaths from heart attacks, diabetes and cancer.10

What's the current status of bariatric surgery in Canada?
Canadian general surgeons have only recently become involved in bariatric surgery, and just a handful use the laparoscopic technique. In 2004, there were approximately 1,800 weight loss surgical procedures done in Canada,11,12 treating < 1% of morbidly obese individuals in this country. Of these, 80% were open procedures and 20% were done laparoscopically (7% gastric banding, 13% Roux-en-Y gastric bypass).

Up until February 2002, all bariatric surgery in Canada was performed via standard open incision. However, this leads to wound infection and/or incisional hernia in 1 out of every 4 patients. The only way to eliminate such complications is to avoid making a large cut down the middle of the belly, i.e. use a laparoscopic approach. We performed the first laparoscopic Roux-en-Y isolated gastric bypass at the MUHC on February 8, 2002. To date, the Bariatric Surgery Section of the Division of General Surgery, MUHC, has completed over 3,400 weight loss surgical procedures - the last 1,000 by laparoscopic approach.