Obesity has become a global problem. The definition and classification of obesity is based on the body mass index (BMI), which is calculated as weight in kilograms divided by height in meters squared. An estimated 1.7 billion adults worldwide are now considered overweight (BMI > 25 kg/m2). Of these, 300 million are obese (BMI > 30 kg/m2). In the United States, two-thirds of adults are overweight, one-third of adults are considered obese, and almost 5% are morbidly obese (BMI > 40 kg/m2). In addition, the number of obese children has more than doubled over the past 3 decades to 16%. The more than 50 million obese Americans are at risk of developing numerous obesity-related health problems, including hypertension, diabetes, and coronary artery disease, to name just a few (Table 68-1).

Currently, the annual cost for treating obesity and its related comorbid conditions is estimated at $100 billion. Obesity accounts for more than 100,000 premature deaths annually and is considered the second most preventable cause of death, after cigarette smoking.

To date, surgery is the most effective means of achieving and maintaining long-term weight loss in obese patients. Weight loss, measured as percentage of excess body weight loss (EBWL is calculated as weight loss/excess weight × 100), and improvement in comorbid conditions varies with the different types of procedures. Maximum weight loss is most often seen in the first 1 to 2 years after surgery.

Roux-En-Y Gastric Bypass

The Roux-en-Y gastric bypass (RYGB) is currently the most common bariatric procedure performed worldwide. Much of the popularity stems from the ability to perform the surgery laparoscopically and the significant weight loss that can be achieved by the patients. The Swedish Obese Subjects Study, the largest study on weight loss surgery to date and the study with the longest follow-up, reports a mean percent weight loss of 32.5% of total body weight (percent of total weight loss is roughly equal to half of EBWL) 1 to 2 years after gastric bypass and 25% 10 years post-bypass. A 2004 meta-analysis by Buchwald et al, reported a mean EBWL of 61.6% after 1 to 2 years, which is comparable to the Swedish Obese Subjects Study.

Roux-en-Y gastric bypass also provides excellent improvement and even remission of comorbid conditions (Table 68-2).

More than 75% of patients with diabetes undergoing RYGB will have remission of their diabetes. Here remission is defined as discontinuation of all diabetes-related medications as well as the ability to maintain blood glucose levels within the normal range.

Roux-en-Y gastric bypass patients will likely also have remission of their hypertension. Multiple studies show improvement and even resolution of hypertension in approximately 65–85% of patients.

Hyperlipidemia, hypercholesterolemia, and hypertriglyceridemia are also greatly improved in more than 90% of patients after gastric bypass surgery. In Buchwald’s meta-analysis, total cholesterol levels were seen to decrease by 0.96 mmol/L, LDL by 0.89 mmol/L, triglycerides by 1.07 mmol/L, and HDL was seen to increase by 0.05 mmol/L.

In addition to the comorbidities mentioned above, obstructive sleep apnea is reported to be improved or resolved in 80–90% of patients after gastric bypass. Eighty-five percent of morbidly obese patients with gastroesophageal reflux disease (GERD) reported complete resolution of symptoms after RYGB. Although more difficult to quantify, patients have also reported improvements in depression, joint pain, stress incontinence, infertility, self-esteem, and overall quality of life.

Laparoscopic Adjustable Gastric Banding

Laparoscopic adjustable gastric banding (LAGB) is another popular bariatric procedure both in the United States and worldwide. Although technically less challenging than RYGB, the LAGB requires frequent clinic visits in order to properly adjust the band and maintain the proper amount of gastric restriction and thereby weight loss. Studies have shown good weight loss results with LAGB. The Swedish Obese Subjects Study reports 20% total body weight loss 1 to 2 years after LAGB and 14% 10 years post-banding. Meta-analysis data shows a similar 47.5% EBWL after 1to 2 years.

As with RYGB, LAGB also provides excellent remission or improvement in comorbidities. Multiple studies report remission of diabetes in 50–80%, lower than in patients undergoing RYGB. In addition, Abbatini et al showed that time to remission is longer in patients with LAGB (12 months) when compared to patients who underwent RYGB (3 months).

Although LAGB provides improvement and remission of hypertension, the effect is not as great as after RYGB (45–70% vs. 65–85%). Lipid profiles are also improved after LAGB, but again, not as significantly as after RYGB. Hyperlipidemia, hypercholesterolemia, and hypertriglyceridemia improve in approximately 60%, 80%, and 75% respectively after LAGB. Based on meta-analysis data, total cholesterol, LDL, and triglyceride levels decrease by an average of 0.3 mmol/L, 0.11 mmol/L, and 0.76 mmol/L respectively, while HDL increased by an average of 0.12 mmol/L.

Symptoms of sleep apnea were reported to be improved in 95% of patients post-LAGB. Menstrual irregularities and GERD have also been reported to improve significantly after LAGB as well.

Malabsorptive Procedures

Malabsorptive procedures include jejunal-ileal bypass, which is now never performed, biliopancreatic diversion (BPD), and duodenal switch (DS). Many experts believe that DS provides greater early weight loss than RYGB; however, few studies comparing these two procedures are available. Skroubis et al, in a randomized study of 160 morbidly obese adults, compared RYGB results to the results of their variation of BPD/DS. Eighty patients were randomized to undergo RYGB while the other 80 underwent BPD/DS. Their study showed that even after 2 years, 100% of the BPD/DS patients maintained a greater than 50% EBWL while only 88.7% of RYGB patients were able to maintain similar weight loss. These numbers are consistent with Buchwald’s 2004 meta-analysis that found that average weight loss 1 to 2 years following BPD/DS was 70.1% EBWL, compared with 61.6% in the RYGB patients. In long-term follow-up, more calories lost in fecal fat are balanced by more calories eaten.

Although BPD/DS may be a more complex procedure, patients who undergo this procedure appear to have the best outcomes with regard to resolution of comorbidities. At the 2-year follow-up in the study by Skroubis et al, glucose intolerance, hypercholesterolemia, hypertriglyceridemia, and sleep apnea had completely resolved in both the BPD/DS and RYGB groups. However, while 100% of diabetic patients undergoing BPD/DS experienced remission of the disease, only 70% of RYGB patients with diabetes did so. Similarly, 81% of BPD/DS patients who had suffered from hypertension preoperatively were normotensive at 2-year follow-up, while only 63% of RYGB patients who were hypertensive reached a normotensive state. Lipid metabolism also followed the same pattern: both the BPD/DS and RYGB groups showed decreases in total cholesterol, triglycerides, LDL, and an increase in HDL; however, changes in total cholesterol, LDL, and HDL in the BPD/DS group were significantly (p < 0.005) greater than the RYGB group.

The data from Skroubis et al’s study is consistent with Buchwald’s large meta-analysis that showed remission of diabetes in 97% of patients 1 to 2 years after BPD/DS. Hypertension is also shown to have resolved in a larger number of patients after this malabsorptive procedure (83%) when compared to RYGB. Hyperlipidemia, hypercholesterolemia, and hypertriglyceridemia showed vast improvement after BPD/DS according to Buchwald’s analysis. Ninety-nine percent of those with hyperlipidemia, 87% of patients with hypercholesterolemia, and 100% of patients with hypertriglyceridemia have normal lipid profiles postoperatively. On average, total cholesterol, LDL, and triglycerides dropped by 1.97 mmol/L, 1.36 mmol/L, and 0.8 mmol/L respectively. HDL increased by 0.07 mmol/L.

Sleep apnea is also greatly improved after BPD/DS with reported improvement or remission in more than 85%. Additionally, although more difficult to quantify, patients have reported significant improvements in depression, joint pain, stress incontinence, infertility, self-esteem, and overall quality of life.

Although there is great improvement of comorbid conditions, the improved resolution of these conditions must be balanced against the increased likelihood for vitamin and nutritional deficiencies.

Sleeve Gastrectomy

Laparoscopic sleeve gastrectomy (SG) has recently gained popularity as a singular operation for weight loss. This procedure was initially used as the first stage of a 2-stage DS operation. Because a gastric tube of 100–150 ml is created, SG was originally thought to be a purely restrictive procedure. However, a recent study by Peterli et al has shown a post-SG impact on incretin secretion similar to post-RYGB. Abbatini et al have shown that remission of diabetes after SG occurs at the same early time course and in as high a percentage of patients as RYGB, and earlier and more frequently than in LAGB patients. The data from these studies suggest that although none of the intestine is bypassed, a hormonal change is still achievable.

In small, noncontrolled studies, weight loss results after SG rivaled that of RYGB. In some small series, weight loss after SG was similar to weight loss after adjustable gastric banding. Excess body weight loss has been reported anywhere from 40–80% after 1 year. Because sleeve gastrectomy on its own is a relatively new procedure, few long-term studies or randomized controlled trials are available. However, it is clear that sleeve gastrectomy is effective in achieving significant weight loss and remission of comorbidities and will likely have long-term results between that of RYGB and LAGB.

A healthy diet and exercise should be integral to any health care regimen. However, medical management alone for treatment of morbid obesity has a high failure rate. Long-term maintenance of more than 10% EBWL is extremely uncommon with medical management alone. Therefore, based on the 1991 consensus statement on bariatric surgery for morbid obesity issued by the NIH, it is recommended that patients with BMI greater than 40 kg/m2 or 35 kg/m2 with two or more significant obesity-related comorbidities (Table 68-1) who have failed other methods of weight loss be referred to a bariatric surgeon.