Weight loss scale calendar postbariatric surgery: call for standardized prediction

Background: Candidates for bariatric surgery need realistic targets for weight loss after surgery and the surgeons need to ensure that the patients are on the way to successful weight loss. This study aimed to present a weight loss calendar estimating the average loss in BMI per week after the surgery and to introduce a simple formula to help make an easy and reliable prediction of the weight loss outcome after bariatric surgery. Patients and Methods: This is a retrospective study that included patients who were consecutively recruited for bariatric surgery. During the postoperative follow-up visits, the patients’ weight loss data were recorded and analyzed. The study cohort was randomly split into a training group (to derive the regression models) and a validation group (to validate the obtained model). Results: The mean preoperative BMI was 47.8 ± 8.3 kg/m 2 . At the 12-month follow-up, the mean BMI was 30.04 ± 5.3 kg/m 2 , the mean percentage of excess weight loss (EWL %) was 80.9 ± 18.7 and the mean percentage of total weight loss % was 36.9 ± 5.8. The regression equation was formulated as follows: 1-year EWL % = 139.71 + (- 0.291 × age) + (- 0.981 × baseline BMI) + (0.95 × 2-week EWL %) + (- 17.151 × previous bariatric procedure). The regression formula was: 1-year BMI = (- 3.61) + (- 0.079 × age) + (0.539×baseline BMI) + (4.977 × previous bariatric procedure). Conclusion: The patient’s age, baseline BMI and history of previous bariatric procedures were significant predictors of the 1-year BMI. The same variables, combined with the early postoperative EWL %, significantly predicted the 1-year EWL %.