The Dutch bariatric weight loss chart: A multicenter tool to assess weight outcome up to 7 years after sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass

Abstract Background Current methods for weight-loss assessment after bariatric-surgery do not meet the high standards required to accurately judge patient-outcome in a fair and evidence-based way. Objectives To build an evidence-based, versatile tool to assess weight-loss and weight-regain and identify poor responders up to 7-years after gastric-bypass and sleeve-gastrectomy, for any preoperative body-mass-index(BMI). Setting Multicenter-observational-study. Methods Bariatric weight-loss-charts were built with standard-deviation(SD) percentile(p)-curves p+2SD/p+1SD/p50(median)/p-1SD/p-2SD, based on all last measured weight-results after primary laparoscopic Roux-en-Y-gastric-bypass and sleeve-gastrectomy, performed in three large bariatric-centers, expressed with percentage-total-weight-loss(%TWL) and percentage-alterable-weight-loss(%AWL), a special BMI-independent metric. The p-1SD %AWL-curves were compared to popular bariatric-criteria 50% excess-weight-loss(%EWL) and 20%TWL. The p50-%TWL-curves were compared to %TWL-outcome in literature (external-validation). Results In total, 9393 patients (5516 gastric-bypass, 3877 sleeve-gastrectomy, baseline-BMI 43.7(±SD5.3)kg/m 2 , age 43(±SD10.9)years, 20% male, 21% type-2-diabetes) had mean follow-up 26(range0-109)months, with 0.09% 30-day mortality. Independent outcome is presented in percentile-charts for %AWL and %TWL. Percentile-curves p+2SD/p+1SD/p50/p-1SD/p-2SD showed for gastric-bypass 72/62/50/38/28%AWL at nadir, 66/55/43/30/17%AWL at 4-years, 64/52/38/25/11%AWL at 7-years and for sleeve-gastrectomy 69/58/46/34/22%AWL, 65/53/38/23/12%AWL and 63/51/35/22/9%AWL respectively. Bariatric-criteria 50%EWL and 20%TWL matched with most insufficient results for sleeve-gastrectomy, but not for gastric-bypass (low specificities). Both p50 %TWL-curves are comparable with Long-term weight-loss in bariatric-literature. Conclusions Just as well-known growth-charts are essential for pediatrics, weight-loss charts should become the tools of choice for bariatrics. These multicenter-charts are baseline-BMI independent, superior to current bariatric-criteria and quite intuitive to use. They allow to readily detect poor responders in any postoperative phase, monitor the effect of extra counseling, judge weight-regain and manage patient expectations.