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Research Considerations in Obesity Surgery

2002; Wiley; Volume: 10; Issue: 1 Linguagem: Inglês

10.1038/oby.2002.10

1550-8528

John G. Kral, Robert E. Brolin, Hēnry Buchwald, Walter J. Pories, Michael G. Sarr, Harvey J. Sugerman, Bruce M. Wolfe,

Cardiovascular Function and Risk Factors

Obesity, a metabolic disease of lipid storage, has reached epidemic proportions worldwide, associated with dramatic increases in type 2 diabetes, hypertension, and pulmonary disease in adults as well as children. Indeed, childhood obesity is considered to be "the largest single public health challenge of this century" (J. C. Seidell at the 11th European Congress on Obesity, May 30–June 2, 2001, Vienna, Austria). Results of nonsurgical treatment of obesity, regardless of severity, are disappointing and have not improved over the last 20 years. In fact the epidemic is expanding. Although surgical treatment of obesity has been demonstrated to be safe and effective in thousands of patients with 10 years or more of follow-up, there remain questions about surgical treatment that may influence selection of patients and monitoring of outcome. For this reason, the National Institutes of Health and the American Society for Bariatric Surgery sponsored a workshop to identify research needs in this field, convening experts in pediatrics, epidemiology, gastroenterology, endocrinology, nutrition, and gastrointestinal surgery (1). The current bariatric operations include gastrointestinal bypasses with intestinal limbs of varying lengths influencing the processing of nutrients and the release of satiety peptides, and gastric restrictive operations such as banded gastroplasties and circumgastric adjustable banding, which limit the reservoir function of the proximal stomach and the ability to ingest a large meal. Gastric bypass operations also have a restrictive component, which, however, is transitory, contributing to initial weight loss. These operations were all developed using open surgical approaches. However, with expertise in bariatric surgery and adequate technical proficiency in minimally invasive techniques, many of the current operations can now be performed safely with a laparoscopic approach, leading to improved perioperative outcomes including decreases in complication rates, length of hospital stay, and time out of work. Although universally more effective than any nonsurgical treatment when evaluated after 5 or more years, there is substantial variability among operations, generally favoring bypass operations with shorter absorptive segments in heavier patients. The severity of the growing global epidemic of obesity and type 2 diabetes especially in children through nongenomic gestational transmission, and the limited ability of nonsurgical treatments to provide durable medically significant weight reduction in obese patients lend urgency to the need for exploring the role of surgical treatment in younger and in less than severely obese patients (body mass index [BMI]: 30 to 35 kg/m2). Lowering the age for bariatric surgery to preadolescence and adolescence raises concerns about the long-term consequences of various surgical procedures, which include development of esophageal disease after restrictive operations and deficiencies after gastrointestinal bypass, as well as concerns regarding the safety of future pregnancies. Although evidence shows that pregnancy outcomes after bariatric surgery are favorable compared with outcomes in the unoperated obese, careful prospective studies are required to evaluate maternal and neonatal insulin resistance and nutritional status in the presence of restrictive or bypass operations in mothers. Such studies are also relevant for defining and determining the timing of postoperative pregnancies and optimal rates and amounts of weight loss in different grades of obesity (grades I to IV: BMI > 30 kg/m2). Just as maternal–fetal overnutrition is detrimental to the fetus in obese pregnancies, there is also the potential for undernutrition-related development of precursors of adult disease in the offspring of surgically weight-reduced mothers. Obesity is associated with abnormalities of esophageal and gastric emptying with increased prevalence over time of gastroesophageal reflux disease, with its associated conditions of Barrett's esophagus (a premalignant condition), and adenocarcinoma of the esophagus. All gastric operations for obesity initially compromise esophageal clearance because of nonyielding outlets from the proximal gastric reservoir. Gastric bypass operations with outlets that dilate with time divert gastric and duodenal contents, reducing acid exposure and preventing bile reflux, relieving gastroesophageal reflux disease. However, concerns about the long-term effects of the purely restrictive procedures with exposure to esophageal dilatation and the fate of banding material and devices in young patients indicate the need for studies specifically designed to evaluate the long-term effects of bariatric operations on the function and morphology of the esophagogastric junction in obese patients. Because weight loss has been associated with increased mortality in epidemiological studies, albeit from underlying disease, and bariatric surgery effectively causes substantial weight loss, there is a need for long-term postoperative studies to assess hard end-points. Furthermore, gastric bypass operations with varying lengths of absorptive segments create disturbances of digestion and absorption with the possibility of serious metabolic sequelae. Although preventable by meticulous monitoring and supplementation, these disturbances have the potential to cause undernutrition, if not frank malnutrition. Active research is needed to determine the effects of each modification of bypass operations on the intake and absorption of specific nutrients. Other areas recommended for additional research include: refinement of criteria for patient selection that should include development of educational programs necessary for informed consent and cooperation with recommended postoperative treatment plans, assessment of long-term psychosocial adjustment, exploration of methods for increasing the availability of bariatric surgery and follow-up care among minorities and poor individuals who are over-represented among the obese, and establishment of a representative national registry including methods for improving follow-up. Given that it is more than 10 years since the 1991 National Institutes of Health Consensus Development Conference: Gastrointestinal Surgery for Severe Obesity (2) and that subsequent accumulation of a substantial body of data has occurred since then, it seems both appropriate and necessary to arrange a new consensus development conference to address among other topics: the efficacy of surgical compared with nonsurgical treatments for obese patients with BMI 30 to 35 kg/m2, laparoscopic bariatric surgical approaches, new restrictive and bypass procedures, and the influence of age on outcomes of surgical treatment of obesity. Bariatric surgery has the potential for providing primary prevention in the obesity epidemic as well as safe and effective treatment in obese patients with comorbidities. Questions remain concerning broadening age criteria, assessing long-term gastroesophageal function after gastric restrictive operations, and the potential for undernutrition after new modifications of bypass operations. However, gastrointestinal surgery for obesity is currently grossly underused in the United States. This study was supported by the National Institutes of Health and the American Society for Bariatric Surgery. The Organizing Committee for the Workshop included John G. Kral, (co-chairman), Robert E. Brolin (co-chairman), Henry Buchwald, Louis J. Flancbaum, Van S. Hubbard, Samuel Klein, Louis F. Martin, Walter J. Pories, Michael G. Sarr, Harvey J. Sugerman, and Bruce M. Wolfe. Speakers included Thomas A. Buchanan, Henry Buchwald, Michael Camilleri, Peter F. Crookes, Edward W. Gregg, Peter J. Kahrilas, John G. Kral, Lloyd D. MacLean, Michael M. Murr, David I.W. Phillips, Walter J. Pories, Michael G. Sarr, Harvey J. Sugerman, and Bruce M. Wolfe.