Analysis of mid-term weight loss after Roux-en-Y gastric bypass and sleeve gastrectomy: Proposed percentile charts for total weight loss percentages to be used in daily clinical practice.

Introduction: The aim of this study is to analyze weight evolution after the main bariatric surgical techniques (Roux-en-Y gastric bypass [RYGB] and sleeve gastrectomy [SG]) performed at a representative sample of Spanish hospitals in order to develop percentile charts for the percentage of total weight loss during the first 3 years after surgery.

Methods: A retrospective longitudinal cohort study was conducted based on the data provided by 9 Spanish hospitals. Weight data were analyzed both in % total weight loss and % excess weight lost corresponding to the RYGB (n=1,887) and SG (n=1,210).

Results: RYGB continues to be the most frequently performed technique in our sample. In both surgical techniques, maximum weight loss occurred 18 months after surgery. Both techniques followed the same weight evolution, although the % total weight loss values were lower in the case of the SG after 36 months (29.3±10 vs. 33.6±10). Age and gender are decisive in the weight results (better in younger patients for both techniques and better in women for RYGB).

Conclusions: Percentile charts of % total weight loss after bariatric surgery represent a very useful tool and an important advance in the quality of patient management.