Background: Laparoscopic gastric bypass (LGB) has proven efficacy in causing significant and durable weight loss. However, the degree of postoperative weight loss and metabolic improvement varies greatly among individuals. Our study is aimed to identify independent predictors of successful weight loss after LGB.

Methods: Socioeconomic demographics were prospectively collected on patients undergoing LGB. Primary endpoint was percent of excess weight loss (EWL) at 1-year follow-up. Insufficient weight loss was defined as EWL <or=-1 SD from mean EWL. Logistic regression was used in both univariate and multivariate models to identify independent preoperative demographics associated with successful weight loss.

Results: A total of 180 consecutive patients were enrolled over 30 months. Mean preoperative body mass index (BMI) was 48. Mean EWL was 70.1 +/- 17.3% (1 SD); therefore, success was defined as EWL >or=52.8%. According to this definition, 147 patients (81.7%) achieved successful weight loss 1 year after LGB. On univariate analysis, preoperative BMI had a significant effect on EWL, with patients with BMI <50 achieving a higher percentage of EWL (91.7% vs 61.6%; p = 0.001). Marriage status was also a significant predictor of successful outcome, with single patients achieving a higher percentage of EWL than married patients (89.8% vs 77.7%; p = 0.04). Race had a noticeable but not statistically significant effect, with Caucasian patients achieving a higher percentage of EWL than African Americans (82.9% vs 60%; p = 0.06). Marital status remained an independent predictor of success in the multivariate logistic regression model after adjusting for covariates. Married patients were at more than two times the risk of failure compared to those who were unmarried (OR 2.6; 95% CI: 1.1-6.5, p = 0.04).

Conclusions: Weight loss achieved at 1 year after LGB is suboptimal in superobese patients. Single patients with BMI < 50 had the best chance of achieving greater weight loss.