Obesity—Is Surgery Finally Here for This Important CV Risk Factor?

Abstract & Commentary

Synopsis: Effective weight loss was achieved in morbidly obese patients after undergoing bariatric surgery. A substantial majority of patients with diabetes, hyperlipidemia, hypertension, and obstructive sleep apnea experienced complete resolution or improvement.

Source: Buchwald H, et al. JAMA. 2004;292:1724-1737.

Obesity is a significant risk factor in and of itself for the development of coronary artery disease. The Metabolic Syndrome (MS) is a recently defined and rapidly evolving area of clinical and basic research and clinical care and is becoming an important public health issue which is of growing concern since is usually associated with obesity (ie, defined as a body mass index BMI of equal to or greater than 30) which affects approximately 1.7 billion individuals in the world. Of particular interest are the facts that the percentage of overweight adults is highest in the United States1-4 and obesity among children is also on the rise, an alarming trend in view of the fact that early obesity is a strong predictor of later cardiovascular disease. The distribution of body fat may also play a role in the development of coronary heart disease, with abdominal obesity posing a substantially greater risk in both women and men. A waist circumference of 35 inches in women and 40 inches in men is an easily measured marker of increased coronary heart disease risk.

The rise in the prevalence of obesity is associated with dramatic increases in the prevalence of obesity co-morbidities such as type 2 diabetes (probably secondary primarily to insulin resistance), hyperlipidemia, and hypertension, all conditions which are associated with a significant increase in risk for the development of coronary artery disease.

The pharmaceutical industry, in partnership with the medical profession, has been very successful in developing the medications and techniques used to control the 3 important medical conditions (hypertension, dyslipidemia, and glucose intolerance) often found to be in patients with the MS. However, the fourth important feature, obesity also usually found in patients with the MS has been particularly difficult to control. The obesity problem is quite massive since by some estimates, as high as 66% of the US population is considered to be overweight and almost half of these individuals are defined as being obese. Unfortunately diet therapy with and without support organizations has proven to be relatively ineffective in treating obesity over the long term.5,6 In 1991, the National Institutes of Health established guidelines for the surgical therapy (ie, bariatric surgery) of morbid obesity (ie, BMI equal to or greater than 40 or BMI equal to or greater than 35 in the presence of significant co morbidities).

The literature with respect to the outcomes after bariatric surgery is quite extensive but had not been previously reviewed systematically nor subjected to a meta-analysis. Buchwald and colleagues corrected this deficiency by performing a meta-analysis of all articles on bariatric surgery published in the English language between 1990 and 2003.7 After reviewing 2738 citations, they extracted 136 studies which included a total of 22,094 patients of which 72.6% were women with a mean age of 39 years. Excess weight loss occurred in 47.5% of the patients who underwent gastric banding, in 61.6% of gastric bypass patients, in 68.2% of gastroplasty patients and in up to 70.1% of patients who were subjected to bilio-pancreatic diversion or duodenal switch; the mean percentage was 61.2% for all patients and procedures. Operative mortality ranged from 0.1-1.1%. Diabetes was completely resolved in 76.8% of patients and resolved or improved in 86.0%.

Hyperlipidemia improved in 70% or more of patients. Hypertension was resolved in 61.7% of patients and resolved or improved in 78.5%. Obstructive sleep apnea was resolved in 85.7% of patients.

Comment by Harold L. Karpman, MD

A large, prospective, observational study of 43,457 women with a 12 year follow-up demonstrated that weight loss of at least 9 kg was associated with a 53% reduction in all obesity-related deaths.8 Spurred on by the failure of traditional diet methods to produce permanent weight loss, bariatric surgery has been extensively performed and carefully studied over the past 15 years. Based on the results of Buchwald’s meta-analysis,7 it is clear that the significant weight loss that occurs over the long-term in the majority of morbidly obese individuals after bariatric surgery reverses, eliminates, or significantly ameliorates diabetes, hypertension, hyperlipidemia and obstructive sleep apnea in the majority of the patients. The operative 30-day mortality rates are low and, even after accounting for the pain and anxiety of surgery, the inconveniences of dietary restrictions and exposure to possible surgical complications, the majority of patients have experienced an improved quality-of-life because of improved appearance, and improved social and economic opportunities.9-14

Until recently, obesity had never been categorized as an illness thus preventing Medicare from covering for treatments for obesity-related conditions. In July 2004, Tommy G. Thompson, secretary of the US Department of Health and Human Services, announced that Medicare would remove barriers to covering all services for the treatment of obesity if the available scientific and medical evidence demonstrated their effectiveness in improving health outcomes. Much of the government’s attention to this problem will be focused on gathering evidence to justify payment for diet programs and behavior therapies and obviously, bariatric surgery will also be carefully evaluated to determine whether or not Medicare beneficiaries will be eligible for this aggressive approach for the treatment of obesity itself rather than simply for the treatment only of the consequences of obesity. Hopefully, the report by Buchwald7 will help speed the evaluation process along.

But hold on! Bariatric surgery is not a slam dunk. Although the 30-day mortality rate is low, postoperative complications are not infrequent and, in fact, up to 20% of all patients undergoing bariatric surgery require ICU admission postoperatively. In addition, anastomotic leakage and infection, iron malabsorption (and secondary anemia), vitamin deficiencies with associated disabling neuropathy and other complications of surgery and/or of rapid weight loss can occur. Therefore, obviously, before considering bariatric surgery, patients should be carefully counseled and a psychiatric consultation should be obtained for many reasons but especially to determine the degree of the patient’s motivation and commitment. For the motivated patient, the results of bariatric surgery appear to be quite spectacular resulting in significant excess weight loss in the majority of patients and in significant improvement in co-morbid illnesses (ie, diabetes, hypertension, and hyperlipidemia) which all have clearly been demonstrated to have a significant potential to shorten life and produce symptomatic coronary artery disease. However, is again important to emphasize that for bariatric surgery to be successful, patients must be carefully selected and should be strongly motivated in order to reduce the inevitable incidence of surgical failure in achieving the anticipated weight loss goals.

Dr. Karpman, Clinical Professor of Medicine, UCLA School of Medicine, is Associate Editor of Internal Medicine Alert.

References

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