General Considerations

Obesity has reached epidemic proportions worldwide and continues to exact a high cost in human and monetary terms within the United States. This disease is second only to cigarette smoking as a preventable cause of death and deaths attributable to obesity far outnumber colon cancer. Three hundred thousand people die annually from obesity-related disorders in the United States. In addition, health care costs to treat obesity and weight-related conditions exceed $100 billion annually. This problem is of particular concern because upwards of one-third of adult Americans are obese, with 15% of the population potentially meeting the criteria for bariatric surgery. In short, obesity is a major public health problem that requires aggressive prevention and treatment.

Weight loss surgery has been recognized for decades as an effective treatment of obese individuals. Although the number of bariatric procedures has leveled off over the past few years it is estimated that 340,000 bariatric procedures are still performed annually worldwide. Surgical treatment of obesity is routinely associated with loss of greater than 100 lb. Hence, it is not surprising that patients who undergo such operations can have substantial amelioration of co-morbid conditions.

Bariatric surgery may not be the ideal obesity treatment. However, surgery is currently the most effective and durable treatment of the obese compared with any other available therapy in terms of weight loss, alleviation of comorbid conditions, reduction in mortality risk, and decreased long-term health care costs.

Treatment of overweight and obese individuals is based on the degree of excess body weight and the presence or absence of weight-related conditions. The degree and categorization of excess body weight is routinely based on BMI. A patient’s BMI is calculated by dividing weight in kilograms by the height in meters squared. This index normalizes weight for a given height and is independent of gender. The BMI is generally considered a better classification scheme of excess body weight than the outdated Metropolitan Life tables, which are gender-dependent and require a rough estimate of body frame size.

A BMI of 18.5–25 kg/m² is considered “normal.” A BMI greater than 25 kg/m² is considered “overweight” or “obese” (Table 19–1). Based on these criteria an astounding two-thirds of adult Americans are overweight or obese. A person is considered obese when his or her BMI is 30 kg/m² or higher, and obesity is divided into at least three categories, classes I, II, and III. Bariatric surgeons have defined an additional “super obese” category, which is a BMI greater than 50 kg/m². This extra surgical category has been used in clinical studies when analyzing data and correlating outcomes with preoperative weight class.

Although BMI correlates with excess body fat, it is possible for a highly trained, muscular athlete who in fact is quite lean to have a high BMI. In addition, the association between obesity and mortality appears to be weaker for African Americans as compared with Anglo-Americans. Although the validity of BMI may vary in some patient populations according to their demographic characteristics, including ethnicity, the index has proven to be a clinically relevant measure of obesity that can be linked to disease and mortality risk. For example, the BMI associated with the lowest risk of death is within the normal range for most men and lies within the normal to overweight range for most women (see Table 19–1).

Once BMI is determined, health risk is based on the BMI classification and the presence or absence of weight-related comorbid conditions. The National Institutes of Health (NIH) treatment recommendations start with “healthy eating, exercise, and lifestyle changes” for those with minimal and low health risks and then recommend the addition of diet, pharmacotherapy, or bariatric surgery as health risk increases to the “extremely high health risk” category (Table 19–2). These weight loss treatment recommendations are theoretically based on three parameters: (1) the assessment of the risk of not treating an overweight or obese individual; (2) the risk of a particular weight loss treatment; and (3) the likelihood and degree of benefit from the treatment.

The preceding risk-benefit calculation can be done for those with class III obesity (ie, BMI >40 kg/m²) to determine the treatment of choice. Untreated obesity of this degree is well known to be associated with several conditions, including diabetes, hypertension, sleep apnea, and cardiovascular disease, that lead to increased mortality and years of life lost. Fontaine and colleagues calculated the years of life lost for obese individuals, and found that 30-year-old white men and women with a BMI of 30 can expect to lose 10 years and 8 years of life expectancy, respectively, if their obesity goes untreated. A 20-year-old black man with a BMI of 45 can expect to lose 20 years of his life expectancy if untreated. Hence, the natural history of class III obesity is clearly associated with both increased morbidity and mortality risk, and thus mandates aggressive intervention.

Diets, pharmacotherapy, and behavior modification with or without exercise are the available nonsurgical treatment options for obesity. Diet therapy is the most common self- and primary care provider–prescribed therapy. There is no doubt that diets are highly effective and generally safe—for those who adhere to dietary guidelines. This, unfortunately, is a very small number of individuals. Average weight loss at 12 months is generally quite modest, and the long-term recidivism rate of obesity for those who use diet therapy exceeds 95%. This is true even for obese patients who undergo the most aggressive, ideal nonsurgical weight loss programs under the watchful eye of their primary care physicians. One-third of such patients will not lose any weight relative to their baseline weight and over 80% will fail to have “successful” weight loss at 2 years defined as losing 10% or greater of their baseline weight. Although the efficacy of pharmacotherapy for weight loss is better than diet alone, it is still considered modest compared with the weight loss efficacy of surgery. Diet drugs currently approved by the US Food and Drug Administration (FDA) include orlistat (Xenical), lorcaserin, and topiramate/phentermine. Weight loses for those in the obese category ranges from 5 to 20 lb relative to placebo at 1 year. This magnitude of weight loss has led several obesity experts to believe that pharmacotherapy has a limited role for those with severe obesity.

Behavior modification appears to have limited efficacy and durability as well. For example, Christiansen and colleagues conducted an intensive lifestyle intervention trial in which 249 subjects underwent a 21-week intensive treatment with exercise, diet, and psychological counseling. Although subjects had lost 22 kg at the end of the treatment phase, the average weight loss was reduced to 7 kg 4 years after treatment. In addition, two-thirds of subjects had reduced their weight by less than 5% at the 4-year mark after intensive treatment, with only 28% achieving a weight loss of greater than 10%—the authors’ definition of “success”—at 4 years. The XENDOS trial (XENical in the prevention of diabetes in obese subjects) compared orlistat (trade name Xenical) versus placebo plus behavior modification. This 4-year double-blind trial found a 2.7% weight loss in the placebo plus behavior modification group versus 5.4% in the Xenical group.

Overall, the long-term benefit of nonsurgical treatment of those with class III obesity is likely to be quite limited except for a very small percentage of individuals. In contrast, surgical intervention, as detailed in the following text, has an acceptable risk profile and clear, long-term benefits in terms of weight loss, resolution of comorbid conditions, and reduction in mortality risk. As such, bariatric surgery has the best cost-benefit ratio and is therefore considered the weight loss treatment of choice by the NIH for those with severe obesity.

The indications for surgical treatment of severe obesity are based on the recommendations of the NIH Consensus Development Conference on Gastrointestinal Surgery for Severe Obesity. The first criterion that must be met before considering a patient for bariatric surgery is weight as assessed by BMI. Patients with a BMI of 35–39.9 kg/m² (ie, class II obesity) can be considered for surgical intervention if they have severe weight-related conditions such as diabetes, hypertension, debilitating osteoarthritis, or sleep apnea. Those with a BMI of 40 kg/m² or greater (ie, class III obesity) may be appropriate candidates for bariatric surgery with or without weight-related comorbid conditions. Approval for surgery based on the preceding BMI criteria assumes there are no contraindications to surgery.

Of note, an FDA advisory panel voted to lower the acceptable weight limits for certain types of weight loss surgery in December of 2010. The FDA now recommends that patients with a BMI of 30–35 kg/m² with weight-related comorbid conditions may be acceptable for adjustable gastric banding.

If a patient satisfies the BMI criteria for bariatric surgery, he or she is more fully evaluated. The patient should have an extensive history of previous weight loss attempts prior to seeking surgery. Most patients in this weight category have undergone a wide variety of nonsurgical interventions over several years. There should be no unstable psychological conditions or substance abuse. Many surgeons operate on patients with depression, but decline to operate on those with unstable conditions. For example, a recent suicide attempt may preclude surgery for at least 1 year or more depending on the ability to demonstrate psychological stability. Patients are routinely screened for such psychiatric issues before proceeding with surgery.

Additional consideration is given to the status of major organs. The bariatric surgical patient should not have severe organ dysfunction, which would make perioperative morbidity and mortality risk unacceptably high. Patients with unstable angina, end-stage pulmonary disease, or cirrhosis may have relative or absolute contraindications to bariatric surgery. However, optimization of treatment of such conditions may improve a patient to the point where he or she may become a bariatric surgical candidate. Generally speaking, there are no guidelines regarding bariatric surgery in those with chronic conditions such as HIV/AIDS or a history of treated cancer. The decision to operate on such individuals must be individualized after careful consultation with the patient, primary care provider, and other specialists who are caring for the individual.

The appropriate age limit for patients considering bariatric surgery is an area of controversy. Adults in the age range of 21–60 years are generally deemed appropriate candidates assuming they have no contraindications to surgery. Several articles have explored operative risk in individuals older than 55 years who undergo bariatric surgery. Although it is generally accepted that operative risk is higher in older compared with younger individuals, it does not seem prohibitive. Accordingly, some surgeons believe that operating on severely obese patients up to age 70 to induce weight loss may be appropriate. In general, a firm age cutoff is not necessary if patients are selected carefully and comorbid medical conditions are brought under optimal control before surgical intervention for weight loss. It should be recognized, however, that older patients require a more extensive evaluation looking for silent organ disease, such as asymptomatic atherosclerotic heart disease. Although such a workup may not prevent a bariatric surgical complication, it will theoretically select for those who have the physiologic reserve to better tolerate and survive a complication if one were to occur. In short, the ultimate decision to proceed in older patients should be based on the specific individual’s risks relative to the potential benefits, and not just age alone.

Adolescent bariatric surgery is being studied as well, given the rise in type 2 diabetes and other weight-related comorbidities in this age group. Initial studies indicate significant benefits in this age group, which is slowly increasing the medical community’s comfort level with having adolescents being considered for bariatric surgery. As with operating in individuals at the other end of the age spectrum, there are special considerations. It is recommended that surgery be reserved for those adolescents with class III obesity (ie, BMI >40 kg/m²) who have weight-related conditions. This is stricter than the adult criterion of class II obesity with weight-related comorbidities. Adolescents should have documented evidence of failure of at least a 6-month nonsurgical weight loss program. In addition, surgery should not be considered in adolescents until the epiphyseal plates are closed and mature bone length has been achieved. Rapid weight loss may adversely affect bone growth due to restricted caloric intake during this critical time of development. Finally, the family support system takes on an especially important role when operating on younger individuals. It is the extremely rare individual who at so young age does not absolutely require the full support of family. Thus, patient evaluation in the very young essentially mandates extensive evaluation of the patient’s family and support network as well.

One final consideration of bariatric surgery in adolescents is the relative advisability of gastric bypass versus adjustable gastric banding or sleeve gastrectomy (see the description of these procedures in the next section). The gastric bypass requires cutting and rerouting of the intestines, permanently altering the patient’s anatomy with unknown long-term effects in adolescents. In addition, the bypassed stomach remnant and duodenum make endoscopic evaluation quite difficult if indicated at some time in the future. The laparoscopic adjustable band does not permanently alter patient anatomy and can be removed, thereby returning the anatomy to normal if necessary. However, the long-term (ie, 50 or more years) effects of a band in young individuals are completely unknown. The sleeve gastrectomy alters the stomach anatomy. However, the stomach remains in continuity with the duodenum allowing for lifelong surveillance with endoscopy as indicated. These latter two procedures may or may not be more appropriate for the very young. Although there is a great deal to learn about adolescent bariatric surgery, some form of such surgery may take on an important role given the rapid rise of obesity and obesity-related conditions in this age group.

In general, the decision to proceed with bariatric surgery requires careful evaluation of the patient and analysis of both physical and psychological well-being of the patient. This usually requires a multidisciplinary team with a comprehensive program to support patients preoperatively, during hospitalization, and for a lifetime postoperatively. Procedures available for the treatment of obesity are outlined next.