The dilemma of outcome assessment after operations for morbid obesity

Outcome of 56 patients who underwent horizontal gastroplasty (HGP) and 126 who underwent Roux-en-Y gastric bypass (RYGB) was assessed at 18 months postoperatively according to three definitions of successful weight loss; also, outcome was evaluated in the context of amelioration of obesity-related medical problems. Outcome definitions included the following: I, loss of 25% or more of preoperative weight; II, loss of 50% or more of excess weight; III, loss to within 50% of ideal body weight. To evaluate the impact of preoperative weight on success rate, patients were divided into two weight groups: "morbidily" obese patients, who were 100 to 199 pounds overweight (n = 146), and "super"-obese patients who were 200 pounds or more overweight (n = 36). Weight loss was significantly greater with RYGB versus HGP by each of the three definitions of success. Medical problems either improved or resolved with weight loss in 95% of cases. There were statistically significant differences in success rate depending on outcome definition in both HGP and RYGB patients. Success rate ranged from zero in super-obese HGP patients by Definition III to 97% in super-obese RYGB patients by Definition I. Although super-obese patients lost more pounds than the lighter morbidly obese patients, a significantly lower number of super-obese patients lost within 50% of ideal weight. Super-obese patients must lose more weight to reduce their actuarial risk. These results show that the definition of successful outcome may significantly influence the overall success rate in a large series of bariatric surgical patients.