Selection of patients for anti-obesity surgery.

Obesity is a disease with many comorbidities, some of which increase perioperative risk and most of which are improved or even cured by weight loss effectively achieved by surgery. Since anti-obesity surgery is "behavioral surgery", outcome is independent of the technical performance of the operation and patient selection is critical. Pre- and postoperative patient education is more important than in other gastrointestinal surgery. For example, knowledge of the "Rules of eating" and the "Rules of vomiting" are essential for outcome of gastric restrictive surgery. Indications for bariatric surgery are evolving as safety is increasing and more long-term data unequivocally demonstrate its effectiveness, leading to adjustments downward in body mass index and minimum age. However, outcome predictors are lacking, though it is recognized that patient knowledge, psychosocial adaptation and motivational factors including secondary gain and other benefits to remaining obese are important. Discrepancies between patients' weight goals, "ideal" or healthy weight for post-obese individuals and realistic weight loss based on body composition and energy balance, contribute to subjective assessment of quality of life after bariatric surgery. Well-designed observational studies rather than randomized trials, which are both ethically and scientifically flawed, are needed to improve patient selection. Until valid outcome predictors have been identified, a staged approach to bariatric surgery entailing long-term reoperation rates of up to 30% will prevail.