The Role of Surgery in the Treatment of Severe Obesity

Definition and Scope of the Problem
The Significance of Obesity
Non-Surgical Treatments of Obesity
Surgical Treatment of Severe Obesity
Conclusion
 

Definition and Scope of the Problem

Obesity is a disease defined as an excess of adipose or fat tissue that can produce adverse health effects. It is currently the most common chronic disease in the United States. Over half of American adults are overweight or obese, and the World Health Organization has recently declared obesity a worldwide epidemic.

In practice, the presence of obesity is usually determined by calculations based upon both height and weight. The preferred parameter is called the Body Mass Index (BMI). BMI is calculated using a formula (weight in kilograms/height in meters2). Normal BMI is between 20 and 24 kg/m2. An individual is considered overweight with a BMI of 25 to 29, obese with a BMI of 30 to 34, severely obese with a BMI of 35 to 39, and clinically severe or morbidly obese with a BMI in excess of 40. For an adult male of average height, a BMI of 40 corresponds to approximately 100 pounds above ideal body weight (IBW). An estimated five percent of the population is severely obese and an additional three percent are morbidly obese, totaling 14 million people, and the number is growing. Obesity is more common in women, Hispanics, and African-Americans, and increases with age (Table 1).
 

The Significance of Obesity

Obesity exerts a tremendous impact on the physical, psychological, social, and economic health of our nation. It is an independent risk factor for mortality from all causes, with the death rate and overall health risk increasing as the degree of obesity increases (Table 2). Obesity is responsible for 300,000 preventable deaths each year in the United States, second only to smoking. In addition, obesity is associated with numerous comorbid conditions, some potentially life-threatening and others lifestyle-limiting. These conditions are listed in Table 3.

The economic and psychosocial ramifications of obesity are considerable as well. In aggregate, the cost of obesity to society has been estimated at about $100 billion per year or almost 10 percent of total healthcare costs. The social and psychological functioning of obese patients differs from that of other chronic physical conditions such as asthma, diabetes, and musculoskeletal deformities. Obesity also appears to impact negatively on vocational, academic, and healthcare opportunities. There is also evidence that physicians and health professionals harbor negative perceptions toward obese patients.

Successful weight loss is associated with improvement in these comorbid conditions and patient self-image, at least in the short term. In addition, successful long-term weight loss leads to improved employability and decreased long-term healthcare costs.
 

Non-Surgical Treatments of Obesity

Dieting is the most common form of treatment for obesity. Experts estimate that over one-third of Americans are trying to lose weight at any time, at a yearly cost exceeding $30 billion dollars. Unfortunately, diets do not work well for people with clincially severe obesity (CSO) and the best results from studies show that even with behavior modification and nutritional counseling, most people will regain most of their lost weight within two years.

Drugs have also been used to treat obesity. In order for drugs to be effective in patients who are severely overweight, they must be given continuously, just like treatment for high blood pressure or diabetes. In the past, these amphetamine-like drugs were addictive and illegal. Newer non-addictive drugs are now available; however, there are concerns about their safety when used long-term. Finally, most studies have shown that weight loss with drugs is usually about 45 pounds.

Exercise is a valuable aid in losing weight, but more important for maintaining weight loss.
 

Surgical Treatment of Severe Obesity

Surgical treatment of clincially severe obesity has been thoroughly evaluated by numerous national and international health organizations. These include the National Institutes of Health (1991 and 1998), Shape-Up® America and the American Obesity Association (1996), the American Heart Association (1997), the American Dietetic Association (1997), and the World Health Organization (1998). In each of these analyses, surgical treatment of clinically severe obesity was endorsed. A summary of statements from these organizations endorsing the surgical treatment of clinically severe obesity is presented in Table 4. The general guidelines for patient selection currently in use in clinical practice are summarized in Table 5.

There are three operations for the treatment of obesity that are currently popular in the U.S.: the vertical banded gastroplasty (VBG), the Roux-en-Y gastric bypass (RYGB) and the biliopancreatic diversion with duodenal switch (BPD-DS).

Figure 1: Vertical Banded Gastroplasty


The VBG is formed by making a small pouch at the top of the stomach with a capacity of one ounce. The outflow from the pouch into the rest of the stomach is reinforced with a band to prevent stretching. The VBG works by limiting the amount of food that can be consumed.

Figure 1: Vertical Banded Gastroplasty


The VBG is formed by making a small pouch at the top of the stomach with a capacity of one ounce. The outflow from the pouch into the rest of the stomach is reinforced with a band to prevent stretching. The VBG works by limiting the amount of food that can be consumed.

Figure 2: Roux-en-Y Gastric Bypass

The RYGB also has a one-ounce stomach pouch. This pouch, however, is completely separated from the rest of the stomach. A portion of small intestine is then rerouted and connected to the pouch through a new opening. Thus, food intake is limited, as with the VBG, and there is an additional effect caused by the rerouting of the food around the remainder of the stomach.
Figure 2: Roux-en-Y Gastric Bypass

The RYGB also has a one-ounce stomach pouch. This pouch, however, is completely separated from the rest of the stomach. A portion of small intestine is then rerouted and connected to the pouch through a new opening. Thus, food intake is limited, as with the VBG, and there is an additional effect caused by the rerouting of the food around the remainder of the stomach.

Figure 3: Bilio-Pancreatic Diversion with Duodenal Switch


The BPD-DS involves removal of about 60 percent of the stomach and rerouting the food stream around a majority of the intestine. It works primarily by limiting the amount of nutrients that can be absorbed.

Figure 3: Bilio-Pancreatic Diversion with Duodenal Switch


The BPD-DS involves removal of about 60 percent of the stomach and rerouting the food stream around a majority of the intestine. It works primarily by limiting the amount of nutrients that can be absorbed.
Figure 1: Vertical Banded Gastroplasty


The VBG is formed by making a small pouch at the top of the stomach with a capacity of one ounce. The outflow from the pouch into the rest of the stomach is reinforced with a band to prevent stretching. The VBG works by limiting the amount of food that can be consumed.

Figure 2: Roux-en-Y Gastric Bypass

The RYGB also has a one-ounce stomach pouch. This pouch, however, is completely separated from the rest of the stomach. A portion of small intestine is then rerouted and connected to the pouch through a new opening. Thus, food intake is limited, as with the VBG, and there is an additional effect caused by the rerouting of the food around the remainder of the stomach.

Figure 3: Bilio-Pancreatic Diversion with Duodenal Switch


The BPD-DS involves removal of about 60 percent of the stomach and rerouting the food stream around a majority of the intestine. It works primarily by limiting the amount of nutrients that can be absorbed.

In general, the VBG produces the least amount of weight loss, about 40 to 60 percent of excess body weight, whereas the BPD-DS produces the greatest amount of weight loss, about 75 to 80 percent  of excess weight. The RYGB is intermediate, causing 50 to 75 percent  of excess weight loss. In terms of weight regain and nutritional complications, the VBG is associated with the most regain and fewest nutritional problems; the BPD-DS has the lowest weight regain but the most nutritional complications, and the RYGB is in the middle (Table 6). For these reasons, the RYGB is currently the most popular procedure done in the U.S. (about 75 percent), followed by the VBG (15 percent), and the BPD-DS ( 10 percent).
 

Conclusion

Severe obesity is a growing public health problem in the U.S. Surgery provides the most effective treatment, producing the greatest amount of weight loss and best long-term maintenance.

Table 1: Incidence of Overweight and Obesity in the United States
 

Weight Category* BMI 1988-1994Population
Overweight 25-2932 percent57.5 Million
Obese (WHO-I)30-3414 percent25.1 Million
Severe Obesity (WHO-II)35-395 percent9.0 Million
Morbid Obesity (WHO-III)40+3 percent5.4 Million
Total Population54 percent97 Million

* Classification based upon World Health Organization (WHO)

Table 2: Health Risk in Relation to BMI*
 

BMI (kg/m2)Obesity CategoryHealth Risk w/o Medical ProblemsHealth Risk With Medical Problems
< 19UnderweightSlightMinimal
19-24NormalNoneMinimal
25-29OverweightMinimalModerate
30-34Obese (WHO-I)ModerateHigh
35-39Severe (WHO-II)HighVery High
40-50Morbid (WHO-III)Very HighExtreme
50+Super ObeseExtremeVery Extreme

* Classification based upon World Health Organization

Table 3: Medical Conditions Associated with Obesity

Potentially Life-Threatening Conditions

  • Diabetes mellitus (type 2)
  • Hypertension
  • Kidney failure
  • Hyperlipidemia
  • Cardiovascular disease
  • Stroke
  • Obstructive sleep apnea-obesity hypoventilation
  • Cancer (prostate, colon, breast, uterus)

Lifestyle Limiting Conditions

  • Osteoarthritis
  • Liver disease and gallstones
  • Gastroesophageal reflux
  • Urinary stress incontinence
  • Varicose veins and deep venous thrombosis
  • Leg swelling
  • Abdominal wall hernias and skin-fold infections
  • Menstrual irregularity and infertility
  • Depression and social stigmatization

Table 4: Endorsements of Surgical Treatment of Clinically Severe Obesity

National Institutes of Health Consensus Development Conference (1991)
“The surgical procedures currently in use [such as Roux-en-Y gastric bypass and vertical banded gastroplasty] are capable of inducing significant weight loss in severely obese patients, which in turn, has been associated with amelioration of most of the comorbid conditions that have been studied.”

Shape-Up® America /American Obesity Association: Guidances for the Treatment of Adult Obesity (1996)
“Surgical treatment for obesity should be considered for patients with a BMI > 40 or a BMI > 35 with comorbidities or other risk factors.”

American Dietetic Association – Weight Management (1997)
“Surgical treatment of obesity should be limited to patients with a BMI over 40 or BMI over 35 and severe comorbid conditions related to the obesity… Improvements in cardiovascular functioning, lipid profile, sleep apnea, physical activity, and work abilities have been reported.”

American Heart Association Science Advisory and Coordinating Committee: Obesity and Heart Disease" (1997)
“When the BMI is > 35 and comorbidities exist, gastrointestinal surgery becomes a consideration. When the BMI is > 40, surgery is the treatment of choice. The experience of the surgeon and type of operation chosen predict outcome. In general, a Roux-en-Y gastric bypass is superior to gastric plication.”

World Health Organization - Obesity: Preventing and Managing the Global Epidemic (1998)
“Surgery is now considered to be the most effective way of reducing weight, and maintaining weight loss, in severely (BMI > 35) and very severely obese (BMI > 40) subjects. On a kg/weight loss basis, surgical treatment has been estimated after four years to be less expensive than any other treatment.”

NIH, National Heart Lung and Blood Institute: Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults – The Evidence Report (1998)
“Gastrointestinal surgery (gastric restriction [vertical gastric banding] or gastric bypass [Roux-en-Y]) can result in substantial weight loss, and therefore is an available weight loss option for well-informed and motivated patients with BMI > 40 or BMI > 35, who have comorbid conditions and acceptable operative risks.”

Table 5: Guidelines for the Surgical Treatment of Clinically Severe Obesity

  • Patients must have a BMI over 40 kg/m2 or a BMI over 35 kg/m2 with severe associated medical problems.
  • Patients should have failed or be likely to fail dietary and/or drug treatment.
  • Patients must have no contraindications to surgery, such as uncontrolled binge-eating disorder, anorexia/bulimia, terminal malignancy, etc.
  • Patients must be able to comprehend the nature of the procedure and provide voluntary informed consent.
  • Patients must be willing to commit to long-term follow-up.

Table 6: Comparison of Various Weight Loss Operations

VBGRYGBBPD-DS
Weight Loss (percent of excess body weight lost)40-6060-7570-80
Weight Regain (percent) 25-4010-15<10
Limited Amount of Food IntakeYesYesNo
Types of Food RestrictedMeat, raw fruit and vegetablesSimple sugarsFats
Excessive Gas/FlatusNoRareCommon
Dumping SyndromeNoYesNo
Protein MalnutritionNoNoYes
Vitamin DeficiencyNoYesYes
Calcium DeficiencyNoNoYes
Iron, Vitamin B12 DeficiencyNoYesYes
Technical EaseEasiestIntermediateMost Difficult
Need for Operative RevisionCommon (weight regain, stricture, ulcer)Rare (weight regain, stricture, ulcer)Unusual (malnutrition)
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