Rebecca Kraus1, Daniel J Stekhoven2, Ulrich Leupold3, Walter R Marti3. 1. Department of Surgery, Kantonsspital Aarau, Aarau, Switzerland. rebecca_kraus@bluewin.ch. 2. Quantik AG, Berikon, Switzerland. 3. Department of Surgery, Kantonsspital Aarau, Aarau, Switzerland.
Abstract
BACKGROUND: Several studies investigated the impact of preoperative weight loss on bariatric surgery outcome. However, they mostly focus on small groups of patients or lack updated statistical support. METHODS: Two hundred and thirty-nine consecutive patients undergoing laparoscopic, proximal Roux-en-Y gastric bypass at our institution between September 2009 and November 2015 were studied. Patients were operated by the same surgeon, applying a standardized technique and followed a 500-kcal/day preoperative diet, starting 14 days before surgery. Body weight was measured before diet, at surgery, and at least three times postoperatively. A linear mixed effects (LME) model and Benedict and Harris formula were used to assess association of pre- and postoperative weight loss up to 2 years postoperatively. RESULTS: Patients' (184 females) initial weight was 121.7 kg (females 117.2 kg; males 136.6 kg). They lost on average 5.3 kg (females 4.7 kg; males 7.0 kg) pre- and 36.8 kg (females 36.7 kg; males 37.0 kg) postoperatively, within 2 years. Average excess weight loss (EWL) was 67.2% (females 66.6%; males 67.4%). In 205 patients (154 females), EWL exceeded 50%. Longitudinal data analysis according to LME showed a significant impact of pre- on postoperative weight loss (p < 0.001, likelihood-ratio test, LRT). These effects were undetectable if patients were evaluated by non-parametric analysis based on application of the Benedict and Harris formula. CONCLUSIONS: Preoperative dietary success is associated with postoperative weight loss. Effects predicted by the LME model are most pronounced in the first 4-6 months after surgery and are fading away within 24 months postoperatively. External factors not considered in this study might dominate in later phases.
BACKGROUND: Several studies investigated the impact of preoperative weight loss on bariatric surgery outcome. However, they mostly focus on small groups of patients or lack updated statistical support. METHODS: Two hundred and thirty-nine consecutive patients undergoing laparoscopic, proximal Roux-en-Y gastric bypass at our institution between September 2009 and November 2015 were studied. Patients were operated by the same surgeon, applying a standardized technique and followed a 500-kcal/day preoperative diet, starting 14 days before surgery. Body weight was measured before diet, at surgery, and at least three times postoperatively. A linear mixed effects (LME) model and Benedict and Harris formula were used to assess association of pre- and postoperative weight loss up to 2 years postoperatively. RESULTS:Patients' (184 females) initial weight was 121.7 kg (females 117.2 kg; males 136.6 kg). They lost on average 5.3 kg (females 4.7 kg; males 7.0 kg) pre- and 36.8 kg (females 36.7 kg; males 37.0 kg) postoperatively, within 2 years. Average excess weight loss (EWL) was 67.2% (females 66.6%; males 67.4%). In 205 patients (154 females), EWL exceeded 50%. Longitudinal data analysis according to LME showed a significant impact of pre- on postoperative weight loss (p < 0.001, likelihood-ratio test, LRT). These effects were undetectable if patients were evaluated by non-parametric analysis based on application of the Benedict and Harris formula. CONCLUSIONS: Preoperative dietary success is associated with postoperative weight loss. Effects predicted by the LME model are most pronounced in the first 4-6 months after surgery and are fading away within 24 months postoperatively. External factors not considered in this study might dominate in later phases.
Entities:
Keywords:
Gastric bypass surgery; Linear mixed effects model; Preoperative weight loss
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