Analysis of weight loss after bariatric surgery using mixed-effects linear modeling.

BACKGROUND: The standard analysis of bariatric surgery weight outcomes data (using t tests) is well known. However, these uncontrolled comparisons may yield misleading results and limit the range of research questions. The aim of the study was to develop a valid approach to the longitudinal analysis of weight loss outcomes after bariatric surgery using multivariable mixed models. This study has a multi-institutional setting. METHODS: We developed a mixed-effects model to examine weight after gastric bypass surgery while controlling for several independent variables: gender, anastomotic technique, age, race, initial weight, height, and institution. We contrasted this approach with traditional uncontrolled analyses using percent excess weight loss (%EWL). RESULTS: One thousand one hundred sixty-eight gastric bypass procedures were performed between 2000 and 2006. The average %EWL at 1, 2, and 3 years was 71%, 79%, and 76%, respectively. Using weight as the outcome variable, initial weight and gender were the only independent predictors of outcome (p<0.001). %EWL was substantially less accurate than weight as an outcome measure in multivariable modeling. Including initial weight and height as separate independent variables yielded a more accurate model than using initial body mass index. In a traditional uncontrolled analysis, average %EWL was higher in women than men. However, average weight loss was lower, not higher, in women (p<0.001) in our multivariable mixed model. Height, surgical technique, race and age did not independently predict weight loss. CONCLUSIONS: Multivariable mixed models provide more accurate analyses of weight loss surgery than traditional methods and should be used in studies that examine repeated measurements.

The orientation of the antecolic Roux limb markedly affects the incidence of internal hernias after laparoscopic gastric bypass.

BACKGROUND: Internal herniation of the bowel may be a late complication after the laparoscopic Roux-en-Y gastric bypass (RYGBP). A seemingly minor change in technique is described that significantly prevents herniation behind the Roux limb mesentery. We hypothesized that internal hernias behind the Roux limb mesentery occur more frequently when the Roux limb is oriented such that the distal tip is toward the lesser curvature of the gastric pouch with the bowel then curving to the patient's left, compared with the opposite orientation. METHODS: A retrospective chart review was performed of our prospectively collected database. A change in surgical technique occurred June 2003, in an attempt to reduce internal hernia formation. We compared 200 consecutive antecolic left-oriented RYGBP operations performed immediately previous to June 2003 (Group A) with 200 consecutive antecolic right-oriented RYGBP operations performed after June 2003 (Group B). RESULTS: There was an 9.0% rate of internal hernia formation in Group A (18/200) and a 0.5% rate of internal hernia formation in Group B. Internal hernias were repaired an average of 1.2 years after surgery (range 4-30 months, median 14.3 months). The average length of follow-up was 2.1 and 1.6 years in Groups A and B, respectively. All herniations were behind the Roux limb mesentery. The difference in hernia formation after the change in technique was significant (P<0.005). CONCLUSIONS: With a simple change in technique, the incidence of internal herniation behind the Roux limb mesentery may be significantly reduced or eliminated.

Prospective, randomized, multicenter study evaluating safety and efficacy of intragastric dual-balloon in obesity.

BACKGROUND: Intragastric balloons are designed to occupy space within the stomach and induce satiety. The present study evaluated the safety and efficacy of an intragastric dual balloon as an adjunct to diet and exercise in obese patients compared with diet and exercise alone. METHODS: After approval from the institutional review board, patients provided written consent and were randomized to the treatment group (TG) or control group (CG) in a 2:1 ratio. Three sites randomized a total of 30 patients to the TG (n = 21) or CG (n = 9). Patients randomized to the TG underwent endoscopic placement of the dual balloon. Both groups received similar diet and exercise counseling. After 24 weeks, the device was removed. Patient weight, adverse events, and quality of life data were evaluated throughout the 48-week study duration. RESULTS: Our patient population included 26 women and 4 men aged 26-59 years. At 24 weeks, the mean excess weight loss in the TG and CG was 31.8% ± 21.3% and 18.3% ± 20.9%, respectively (P = .1371). At 48 weeks, 24 weeks after device removal, the TG maintained 64% of their weight loss. No deaths, unanticipated adverse effects, early removals, balloon deflations, or balloon migrations occurred. In the TG, 4 patients were readmitted for severe nausea, 1 had asymptomatic gastritis at balloon removal, and 1 patient experienced transient hypoxia during device removal. CONCLUSION: In the present small study, the dual balloon proved easy to use, was associated with a trend toward greater weight loss than the CG, and demonstrated a good safety profile.

Sexual dysfunction is common in the morbidly obese male and improves after gastric bypass surgery.

BACKGROUND: There has been limited research examining the mechanisms and epidemiology of sexual dysfunction in the morbidly obese. Our objectives were to measure sexual function in the morbidly obese man before and after substantial weight loss induced by gastric bypass surgery. STUDY DESIGN: All male patients in undergoing gastric bypass completed the Brief Male Sexual Function Inventory (BSFI) before and after operation. BSFI scores were also compared with published normative controls and analyzed for predictors of change. Mixed models were created to control for age, diabetes, and hypertension. RESULTS: Ninety-seven men with a mean age of 48 years (range 19 to 75 years) and mean body mass index of 51 kg/m(2) (range 36 to 89 kg/m(2)) underwent gastric bypass surgery. On average, preoperative morbidly obese patients reported a substantially greater degree of sexual dysfunction than did published reference controls in all domains, p < 0.001. Increasing weight independently predicted lower domain scores. Mean postoperative followup length was 19 months (range 6 to 45 months). On average, BSFI scores improved from preoperative levels by bivariate analysis in all categories (means+/-SE): sexual drive (range 0 to 8), 3.9+/-0.3 to 5.3+/-0.3; erectile function (range 0 to 12), 6.4+/-0.5 to 8.9+/-0.5; ejaculatory function (range 0 to 8), 4.9+/-0.4 to 6.3+/-0.4; problem assessment (range 0 to 12), 7.4+/-0.5 to 9.6+/-0.5; and sexual satisfaction (range 0 to 4), 1.6+/-0.2 to 2.3+/-0.2; all p < 0.01. On multivariable analysis, the amount of weight loss independently predicted the degree of improvement in all BSFI domains, p < 0.05. After an average 67% excess weight loss, BSFI scores in postoperative gastric bypass patients approached those of the reference controls. CONCLUSIONS: Men with morbid obesity commonly suffer from profound, but reversible sexual dysfunction.