Updating Criteria for Weight Loss Surgery

| April 15, 2011

by Richard J. Joseph, BS; George L. Blackburn, MD, PhD; and Daniel B. Jones, MD, MS, FACS

Mr. Joseph and Dr. Blackburn are from Beth Israel Deaconess Medical Center, Center for the Study of Nutrition Medicine, Boston, Massachusetts. Dr. Jones is from Beth Israel Deaconess Medical Center, Minimally Invasive and Bariatric Surgery, Boston, Massachusetts.

Financial Disclosure: Mr. Joseph and Drs. Blackburn and Jones report no conflicts of interest relevant to the content of this article.

In light of the United States Food and Drug Administration’s recent endorsement of expanded body mass index eligibility criteria for Allergan’s Lap-Band ® Adjustable Gastric Banding System, it is imperative to study the long-term safety and cost effectiveness of laparoscopic adjustable gastric banding surgery. The patient-specific risk factors in weight loss surgery present a challenge to the development of risk stratification models that will help protect the health and safety of the patient. This article will discuss criteria guidelines that should be revisited, reassessed, and perhaps revised; criteria include body mass index; number, severity, and the rate of onset of comorbidities; and more intermediate risk factors. Also of importance will be the comparative analysis of restrictive laparoscopic adjustable gastric banding surgical procedures versus malabsorptive gastric bypass procedures based on the patient’s baseline risk factors and level of adiposity. Retrospective analyses of Class I obese cohorts will be useful in constructing clinical models that can be tested in prospective trials. Such trials will help to determine baseline characteristics in subgroups of the population with obesity that respond most favorably to bariatric surgery.

Introduction

In February of 2011, the United States Food and Drug Administration (FDA) endorsed an application from Allergan, maker of the Lap-Band® Adjustable Gastric Banding System, to expand body mass index (BMI) criteria for use of gastric banding. After initially approving the procedure in June of 2001,[1] the FDA recently agreed to lower eligible BMI from 35kg/m[2] down to 30kg/m[2] with one or more weight-related comorbidity (e.g., hypertension, dyslipidemia, obstructive sleep apnea [OSA]); those with a BMI ≥40kg/m[2] remain eligible without complications. Although Allergan requested removal of the comorbidity requirement for those with a BMI between 35 and 40kg/m[2], the FDA preserved this stipulation. Based on the new standard, which decreases the lower guideline by five BMI points, Allergan estimates that the number of eligible patients will increase from 15 to 18 million to more than 26 million. Although these guidelines are specific to Allergan’s Lap-Band device, this change makes it imperative to study the long-term safety and cost effectiveness of laparoscopic adjustable gastric banding (LAGB) surgery in order to perform risk-benefit and comparative effectiveness analyses in patients with low BMIs.

The FDA approved the new criteria on the basis of findings from LBMI-001, an ongoing, prospective, nonrandomized, multicenter study that is following 149 patients for five years. Its decision was in line with clinical trials[2–6] and expert opinions[7,8] indicating that weight loss surgery may be warranted at BMI levels lower than those recommended by the National Institutes of Health (NIH) 20 years ago (i.e., BMI ≥40kg/m[2] or BMI ≥35kg/m[2] with one comorbidity).

Large, long-term, prospective trials with standardized presurgical assessment and outcome evaluations are needed to determine the frequency of adverse outcomes and the health conditions associated with them. For example, Flum et al[9] characterized preoperative weight loss surgery risks in a prospective, multicenter observational study of 30-day outcomes in 4,776 first-time bariatric surgery patients. The fatality rate was 0.3 percent, and only 4.3 percent of patients experienced major adverse outcomes.
Preoperative risks were classified according to patient-specific characteristics, obesity-related health conditions, functional status, and type of weight loss surgery procedure; outcomes were linked to these variables. Understanding the factors that underly risk is the first step to building, implementing, and testing clinically applicable risk-stratification models that will help protect the health and safety of patients.[10,11]

Many patient-related and other risk factors in weight loss surgery present a challenge to the development of models that accurately predict which treatment will be best for which patient and under which circumstances. BMI, the main criteria for weight loss surgery, is a good place to start revisiting and reassessing risk criteria.[12–14]

A proxy for human body fat based on an individual’s height and weight, BMI works well on an epidemiological level to stratify groups by adiposity and associated health risks. However, when applied to the individual, its usefulness as a health indicator diminishes.[15–16] As a biomarker, it does not account for age,[11,17] fitness, ethnicity,[18] race,[19] gender,[20] or body composition21—all of which may influence surgical outcomes at a BMI of 30kg/m[2].

As a guideline for weight loss surgery, BMI worked well during the field’s early years, when procedures were restricted to patients with severe obesity. Since then, however, multiple clinical series from the United States and around the world have documented that bariatric surgery is safe and effective for patients with a wider range of BMIs.[22,23] Given the inclusion of Class I patients with obesity for the LapBand® and evidence that use of BMI measures discriminates unfairly on the basis of gender, race, age, fitness, and body fat composition, new guidelines that augment BMI should be pursued for all weight loss surgery options in patients with low-BMIs.

In addition to BMI, or perhaps instead of it, the severity of weight-related illnesses, associated biomarkers, and more intermediate risk factors will improve current selection criteria for bariatric surgery. Comorbid conditions in patients with obesity directly contribute to the incidence and severity of complications from weight loss surgery,[24] increase the risk of perioperative mortality,[25] and raise healthcare costs due to postoperative complications.[26]

For Class 1 patients with obesity, the focus should be on presurgical risk factors, such as the rate of onset of metabolic syndrome and changes in insulin sensitivity. This recommendation is based on results from the Swedish Obese Subjects (SOS) trial,[27] the first long-term, prospective, controlled trial to assess the effect of weight loss surgery on cardiovascular events. It showed that insulin level was a better predictor of the effects of surgical treatment on cardiovascular events than BMI, indicating that elevated insulin levels may be better selection criterion for bariatric surgery than high BMI.

Results from prospective, controlled intervention trials will provide information on baseline characteristics in certain subgroups of the population with obesity that respond more favorably to bariatric surgery. In addition, comparison of long-term outcomes on cardiovascular disease, diabetes, stroke, and overall mortality using data from lifestyle intervention trials like Look AHEAD (Action for Health in Diabetes)[28] will help determine which groups are best suited to particular treatments. Retrospective analyses of Class 1 patient cohorts with obesity will be useful in building clinical models that stratify risk and predict outcomes for weight loss surgery that can be tested in prospective studies.

Those who have already incorporated these risk factors and comorbidities into clinical models have reported favorable outcomes. DeMaria et al10 developed an Obesity Surgery Mortality Risk Score (OS-MRS) based on multivariate analysis of preoperative factors contributing to mortality in 2,075 patients from one clinical center. The scale works by assigning one point to each of five preoperative variables, including BMI of 50kg/m[2] or more, male gender, hypertension, known risk factors for pulmonary embolism, and age 45 or more years.10 In a follow-up, multicenter prospective trial, this group showed that the OS-MRS stratified mortality risk in 4,431 patients who underwent gastric bypass.[29]

Yermilov et al[11] created an appropriateness criteria scale based not only on BMI, but also on the severity level of eight comorbidities—prediabetes, diabetes, hypertension, dyslipidemia, sleep apnea, venous stasis disease, chronic joint pain, and gastroesophageal reflux. Using the Rand/UCLA risk-benefit analysis, the researchers found that for a BMI of 32 to 34kg/m[2], patients aged 19 to 64 years with the most severe classification of diabetes qualified for surgery.11 Similarly, Blackstone[30] also improved upon BMI with the metabolic acuity score, which lowered complication rates and incidence of readmissions and reoperations compared to controls in 2,416 bariatric patients.

Beyond incorporating both the number and severity of comorbidities into such models, it will be important to integrate a “velocity” component that measures the rate at which BMI, biomarkers of obesity-related illnesses, and comorbidities are growing worse. Priority for weight loss surgery should be granted to those with the highest number of intractable comorbidities with rapidly accelerating adiposity. Amidst rising demand for LAGB surgery, it may be prudent to limit access of the surgery to patients most at risk for chronic disease and deteriorating quality of life.

The comparative efficacy of LAGB versus other weight loss procedures also deserves further evaluation, particularly in the Class I obese subgroup. Allergan’s LapBand is an adjustable silicon ring surgically implanted around the upper part of the stomach to restrict the amount of food intake. A band inflated with saline regulates how much and how quickly food can pass into the stomach. The LAGB procedure used to implant the LapBand device differs radically from the more permanent, malabsorptive gastric bypass techniques, which include Roux-en-Y gastric bypass (RYGB), biliopancreatic diversion (BP), or duodenal switch (DS).

Some studies show that LAGB produces substantial weight loss and fewer surgical complications than gastric bypass,[9, 31–33] but findings are inconsistent. A recent study from Campos et al measured weight loss, improvement in metabolic function, and quality of life in 185 patients one year after their surgeries. On all those measures, gastric bypass produced far better results than LAGB. Although gastric bypass patients had more complications in the first postoperative month, those who underwent the LAGB procedure had a higher rate of long-term complications and/or greater need for surgical adjustments.[34] The gastric band can be removed, whereas malabsorptive procedures are less easily reversed and carry an increased risk of nutritional deficiency due to malabsorption. Yet with regard to specific comorbidities, particularly diabetes, gastric bypass appears to be a better treatment due to the physiological/hormonal changes related to insulin resistance.[35]

Actually, all procedures have benefits and drawbacks. While it is tempting to try to identify the “best” procedure, it is impossible to do so based on short-term studies, such as LABS-1. Certain surgeons swear by specific procedures for a variety of reasons. Those who perform RYGB often claim that LAGB produces poor long-term outcomes and often requires removal of the band and conversion to bypass.[36] In contrast, those who favor the adjustable band point to its better safety outcomes and equal efficacy.[37]

With patients with Class 1 obesity now qualifying for weight loss surgery, an important consideration will be which surgery will promote better, long-term weight loss maintenance (≥15% body weight over 5 years) and safety. Comparative effectiveness research will be a priority to match procedures to patient-specific characteristics and comorbidities to optimize outcomes and quality of life. This work will facilitate selection of weight loss surgery candidates and help insurance companies establish coverage guidelines.

Weight loss surgery is more effective for most people than diet, exercise, or pharmacotherapy, and thus should be welcomed as a viable strategy for weight reduction and a treatment for obesity-related comorbidities.[38] However, research must demonstrate that long-term health benefits outweigh the risks. Centers of Excellence should publish and compare outcomes to establish best practice benchmarks[39] and regularly reassess policy recommendations for patient safety and medical error reporting.[40]

Considering that 40 percent of gastric bands may need to be revised or removed over the lifetime of its recipients, we must address the fear and reality of weight regain without the band’s satiety-inducing mechanism. A combination of surgical treatment and healthy lifestyle choices optimize outcomes, quality of life, and weight loss maintenance. To help patients achieve these ends, bariatric surgery centers must establish support groups, buddy systems, and other programs that reinforce dietary and behavior changes with and without the band, should it be removed.

As we assess and modify screening criteria and selection processes, weight loss surgery clinics must partner with lifestyle coaches, pharmaceutical developers, dietitians, and exercise physiologists to coordinate therapeutic modalities in ways that will prevent weight regain and enhance each patient’s transition to life after bariatric surgery.[41] While baseline patient-specific characteristics can influence which procedure to perform, an equally important consideration for long-term success and quality of life is the ability of patients to modify eating and lifestyle choices.

Even as use of the Lap-Band grows, new approaches and techniques are already in the pipeline. Despite the FDA’s recent rejections of three weight loss medications—Qnexa, Lorcaserin, and Contrave—the future of pharmacotherapy remains promising. Explorations on the neurocognitive and epigenetic frontiers of obesity research are also opening the door for novel treatments. In the interim, the large patient population now eligible for LAGB surgery provides fertile ground to test, integrate, and optimize ways to produce physically, psychologically, and fiscally beneficial weight loss maintenance.[42,43]

Acknowledgment
The authors thank Rita Buckley for editing of this article.

References
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