Proposal for an Index for Predicting the Success of Sleeve Gastrectomy: a Pilot Study

Abstract

Background: Determining the relationship between remnant gastric volume (RGV) following laparoscopic sleeve gastrectomy (LSG) and the percentage of excess weight loss (%EWL) remains a challenge. The components of RGV appear to play a much more important role than total RGV. We aimed to determine whether there is an optimal ratio between the components of RGV with respect to %EWL and to develop a statistical model to predict %EWL. Materials and Methods: This was a multicentric prospective observational cross-sectional study conducted between 2014 and 2016 with a minimum of 2 years of follow-up. Two university-affiliated hospitals participated in this study. Patients who underwent LSG as treatment for obesity were enrolled in the study. Those who did not consent to postoperative computed tomography (CT) or whose postoperative CT images were not technically suitable for calculating volumes were excluded. Patients whose follow-up was incomplete were also excluded. Out of a total of 82 patients, 63 completed follow-ups and met the inclusion criteria. By dividing RGV into its components (the antrum and body parts), volumetric measurements were made using a novel CT-based software program. RGV was divided by the antrum volume to yield a ratio that we termed the "Sleeve Coefficient" (SC). Taking SC as an independent variable, nonlinear regression analysis was performed to determine the best model for curve estimation of %EWL. The radiologists who measured the RGV components were blinded to the outcomes. Results: The participants were primarily female (56F/7M), with a mean age of 35.9 (+/- 11.9) and a mean preoperative body mass index of 44.8 (+/- 7.4). The best fitted model for predicting %EWL in the second year was the cubic model. In the second year following LSG, the mean %EWL was 76.1% (+/- 18.2%). There was no significant correlation between total remnant volume and %EWL. Optimal %EWL was obtained when the mean SC was 3.3 +/- 1.5 (95% CI: 2.94-3.72). Conclusions: The ratio between RGV and antral (rather than total remaining stomach) volume appears to be of greater importance and utility in predicting %EWL and in managing LSG candidates. The proposed SC should be validated by further studies.