Obesity: Health Risks
Morbid obesity is a disease of excess energy stores in the form of fat (BMI >40 kg/m2). Being overweight is associated with many physical problems which are now well recognized in both the medical community and general population. Serious consequences of severe obesity are well documented and include cardiac dysfunction, pulmonary problems, digestive diseases, and endocrine disorders as well as obstetric, orthopedic, and dermatologic complications. Obesity is also linked to an increased prevalence of cardiovascular risk factors known as Metabolic Syndrome. These include Hypertension, Type 2 Diabetes Mellitus, Hypertriglyceridemia, Hyperinsulinemia and low levels of high density lipoprotein (HDL) cholesterol.
The risk for diabetes has been reported to be about twofold in the mildly obese, fivefold in moderately obese and tenfold in severely obese persons. The duration of obesity is also an important determinant of the risk for developing diabetes. The association between average weight of population groups and the prevalence of non-insulin-dependent diabetes has been repeatedly observed.
Cancer mortality rates are increased in severely obese females; e.g. endometrium (5.4 times), gallbladder (3.6 times), uterine cervix (2.4 times), ovary (1.6 times), breast (1.5 times). Cancer mortality rates are increased in severely obese males; e.g. colorectum (1.7 times), and prostate (1.3 times). The morbidly obese patient is also at risk for affective, anxiety and substance abuse disorders. People who are obese often consider their condition as a greater handicap than deafness, dyslexia or blindness.
Managing Obesity: What are the Options?
For people that are overweight or obese, weight loss can results in significant improvements to their health and decrease the risks for developing many long-term chronic diseases. Statistically significant improvements have been observed in both diabetes and hypertension, with >10 percent weight loss, and in cardiovascular conditions, with only a 5 percent weight loss of overall body fat for overweight patients.
Generally, the first option for weight loss is a change in diet and exercise. Many people have had success when sticking to a realistic plan and making permanent lifestyle changes. However, for those that have struggled with morbid obesity, diet and exercise may not be sufficient to see the degree of change that they require in order to improve their overall health and achieve a healthy weight.
The use of anorectic medications has recently been advocated as a long term therapeutic modality in management of what is clearly a chronic disease. In a nearly four year study, utilizing a two drug regimen of Phentermine and Fenfluramine, behavior modification, diet and exercise, the initial optimistic results have not been sustained, with a one third drop-out rate and a final average weight loss of only three pounds in those who were followed for the four years of the study. This drug combination appears to have an unacceptably high association with cardiac valvular disease and has been withdrawn from therapeutic use because of these potentially life threatening sequelae.
Published scientific reports document that non-operative methods alone have not been effective in achieving a medically significant long term weight loss in severely obese adults. It has been shown that the majority of patients regain all the weight lost over the next five years.
For people who have exhausted other options such as diet and exercise, Bariatric Surgery may be medically necessary to achieve long term weight control for the morbidly obese. Bariatric surgery involves reducing the size of the gastric reservoir, with or without a degree of associated malabsorption. This can assist patient to improve their eating behaviors dramatically, which reduces caloric intake and ensures that the patient practices behavior modification by eating small amounts slowly, and chewing each mouthful well.
Success of bariatric surgical treatment must begin with realistic goals and progress through the best possible use of well designed and tested operations. These have been worked out over the last thirty years, and are now standardized, clearly defined procedures, with well recognized and documented outcome results including the Lap Band, Gastric Sleeve, Gastric Bypass and Duodenal Switch.
Prevention of secondary complications of morbid obesity is an important goal of management. The biological basis for morbid obesity is unknown, though recent work has demonstrated a genetic component of between 25 and 50%. Several studies confirm the influence of genetically determined proteins produced by the fat cell to be among the many mechanisms which have a place in the control of satiety. These studies confirm that morbid obesity is a disease, not a disorder of willpower, as sometimes implied. The physiological, biochemical and genetic evidence is overwhelming that morbid obesity is a complex disorder. Contributing causes include family history, environmental, cultural, socioeconomic and psychological factors.
Is Bariatric Surgery for Anyone?
The option of surgical treatment should be offered to patients who are morbidly obese, well informed, motivated, and acceptable operative risks. The patient should be able to participate in treatment and long term follow-up. A decision to elect surgical treatment requires an assessment of the risk and benefit in each case. Increased abdominal fat or “central obesity” (apple shaped as opposed to pear shaped or “external obesity”) is an important risk factor associated with the major complications of obesity.
Functional impairments associated with obesity are also important deciding factors for surgical treatment. Patients whose BMI exceeds 40 are potential candidates for surgery if they strongly desire substantial weight loss, because obesity severely impairs the quality of their lives. They must clearly and realistically understand how their lives may change after any of the operations.
In the USA and under certain circumstances, less severely obese patients (with BMI’s between 35 and 40) also may be considered for surgery, and in Mexico, patients with BMI 30 or more are considered for surgery. Included in this category are patients with high risk co-morbidities such as life-threatening cardiopulmonary problems (e.g. severe sleep apnea, Pickwickian syndrome, obesity-related cardiomyopathy, or severe diabetes mellitus). Other possible indications for patients with BMI’s between 35 and 40 include obesity-induced physical problems that are interfering with lifestyle (e.g. musculoskeletal, neurological, or body size problems precluding or severely interfering with employment, family function and ambulation).
Available published series report that the immediate operative mortality rate for Vertical Banded Gastroplasty, Roux-en-y Gastric Bypass and Lap band is relatively low. Morbidity in the early postoperative period (i.e. wound infections, dehiscence, leaks from staple breakdown, stomal stenosis, marginal ulcers, various pulmonary problems, and deep thrombophlebitis) may be as high as ten percent or more. Splenectomy is necessary in 0.3% of patients to control operative bleeding. However, the aggregate risk of the most serious complications of gastrointestinal leak and deep venous thrombosis is less than one per cent. In the late postoperative period, other problems may arise and may require reoperation. The mortality and morbidity rates of reoperation are higher (30%) than those of primary operations.
Complications and Risks of Bariatric Surgery
The most frequent “major” complications for bypass patients were GI leak (0.73%), GI hemorrhage or bleeding (0.44%), and small bowel obstruction (0.40%). Simple restrictive procedures (vertical banded gastroplasty, Gastric sleeve) with no bypass were reported to have GI leak (0.47%) and stoma obstruction or stenosis (0.35%) as the most frequent defined major complication. Lap band does not show leaking.
Risk and efficacy of operations for obesity must be understood in the context that severe obesity is a chronic, frequently progressive, life threatening disease. The therapeutic program applied should be designed to be beneficial throughout the patient’s lifetime. Long term follow-up is essential when reporting treatment effectiveness. Weight loss usually reaches a maximum between 18 and 24 months postoperatively. Mean percent excess weight loss at five years ranges from 48 to 74 % after gastric bypass and from 50 to 60% after vertical banded gastroplasty.
Pure gastric restrictive procedures such as vertical banded gastroplasty (VBG), silastic ring gastroplasty (SRG) and adjustable silastic gastric banding (AGB or LAPBAND) all achieve weight loss by restricting volume of intake. Intake becomes a function of the patient’s motivation to chew well and eat slowly. Failure to do so may result in repeated vomiting and isolated cases of protein and vitamin deficiency have been reported in these circumstances. Careful patient follow up is therefore mandatory, with particular emphasis on the first three postoperative months. Adjustable silastic gastric banding (LAPBAND) approved in 2001 for use in the USA following FDA trials can be considered functionally similar to vertical banded gastroplasty.
Gastric bypass with Roux-en-y (RGB) results in ingested food bypassing the gastric fundus, body, antrum, duodenum and a variable length of proximal jejunum. In consequence, these patients are at risk to develop iron deficiency secondary to lack of contact of food iron with gastric acid and consequent reduced conversion of iron from the relatively insoluble ferrous to the more absorbable ferric form. In addition, vitamin B12 deficiency may result in consequence of food no longer coming in contact with gastric intrinsic factor. Vitamin D and calcium absorption may also be reduced since the duodenum and proximal jejunum, which are the preferential sites of absorption, are bypassed by this procedure. Life long supplements of multivitamins, vitamin B12 iron and calcium are mandatory following this procedure. Long-term follow-up is essential for physical, nutritional and metabolic evaluation.
Weight Loss: Benefits
Weight loss surgery has been reported to improve several comorbid conditions such as glucose intolerance and frank diabetes mellitus, sleep apnea and obesity associated hypoventilation, hypertension, and serum lipid abnormalities. A recent study showed that Type II diabetics treated medically had a mortality rate three times that of a comparable group who underwent gastric bypass surgery. Benefits also include increased ambulation, and decreased incidence of clinical depression, among a wide variety of improvements on a long-term basis.
Arturo Rodriguez, MD
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