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Background This is the second updated Enhanced Recovery After Surgery (ERAS®) Society guideline, presenting a consensus for optimal perioperative care in bariatric surgery and providing recommendations for each ERAS item within the ERAS® protocol. Methods A principal literature search was performed utilizing the Pubmed, EMBASE, Cochrane databases and ClinicalTrials.gov through December 2020, with particular attention paid to meta-analyses, randomized controlled trials and large prospective cohort studies. Selected studies were examined, reviewed and graded according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. After critical appraisal of these studies, the group of authors reached consensus regarding recommendations. Results The quality of evidence for many ERAS interventions remains relatively low in a bariatric setting and evidence-based practices may need to be extrapolated from other surgeries. Conclusion A comprehensive, updated evidence-based consensus was reached and is presented in this review by the ERAS® Society.

BackgroundAlthough bariatric surgery is an effective treatment for type 2 diabetes (T2D) in patients with morbid obesity, further studies are needed to evaluate factors influencing the chance of achieving diabetes remission. The objective of the present study was to investigate the association between T2D duration and the chance of achieving remission of T2D after bariatric surgery.Methods and findingsWe conducted a nationwide register-based cohort study including all adult patients with T2D and BMI ≥ 35 kg/m2 who received primary bariatric surgery in Sweden between 2007 and 2015 identified through the Scandinavian Obesity Surgery Registry. The main outcome was remission of T2D, defined as being free from diabetes medication or as complete remission (HbA1c < 42 mmol/mol without medication). In all, 8,546 patients with T2D were included. Mean age was 47.8 ± 10.1 years, mean BMI was 42.2 ± 5.8 kg/m2, 5,277 (61.7%) were women, and mean HbA1c was 58.9 ± 17.4 mmol/mol. The proportion of patients free from diabetes medication 2 years after surgery was 76.6% (n = 6,499), and 69.9% at 5 years (n = 3,765). The chance of being free from T2D medication was less in patients with longer preoperative duration of diabetes both at 2 years (odds ratio [OR] 0.80/year, 95% CI 0.79–0.81, p < 0.001) and 5 years after surgery (OR 0.76/year, 95% CI 0.75–0.78, p < 0.001). Complete remission of T2D was achieved in 58.2% (n = 2,090) at 2 years, and 46.6% at 5 years (n = 681). The chance of achieving complete remission correlated negatively with the duration of diabetes (adjusted OR 0.87/year, 95% CI 0.85–0.89, p < 0.001), insulin treatment (adjusted OR 0.25, 95% CI 0.20–0.31, p < 0.001), age (adjusted OR 0.94/year, 95% CI 0.93–0.95, p < 0.001), and HbA1c at baseline (adjusted OR 0.98/mmol/mol, 95% CI 0.97–0.98, p < 0.001), but was greater among males (adjusted OR 1.57, 95% CI 1.29–1.90, p < 0.001) and patients with higher BMI at baseline (adjusted OR 1.07/kg/m2, 95% CI 1.05–1.09, p < 0.001). The main limitations of the study lie in its retrospective nature and the low availability of HbA1c values at long-term follow-up.ConclusionsIn this study, we found that remission of T2D after bariatric surgery was inversely associated with duration of diabetes and was highest among patients with recent onset and those without insulin treatment.

Intraoperative adverse events and conversion to open surgery are the strongest risk factors for serious complications after laparoscopic gastric bypass surgery. Annual operative volume and total institutional experience are important for the outcome. Patient related factors, in particular age, also increased the risk but to a lesser extent.

Background: Severe obesity is a global public health threat of growing proportions. Accurate models to predict severe postoperative complications could be of value in the preoperative assessment of potential candidates for bariatric surgery. So far, traditional statistical methods have failed to produce high accuracy. We aimed to find a useful machine learning (ML) algorithm to predict the risk for severe complication after bariatric surgery. Methods: We trained and compared 29 supervised ML algorithms using information from 37,811 patients that operated with a bariatric surgical procedure between 2010 and 2014 in Sweden. The algorithms were then tested on 6250 patients operated in 2015. We performed the synthetic minority oversampling technique tackling the issue that only 3% of patients experienced severe complications. Results: Most of the ML algorithms showed high accuracy (>90%) and specificity (>90%) in both the training and test data. However, none of the algorithms achieved an acceptable sensitivity in the test data. We also tried to tune the hyperparameters of the algorithms to maximize sensitivity, but did not yet identify one with a high enough sensitivity that can be used in clinical praxis in bariatric surgery. However, a minor, but perceptible, improvement in deep neural network (NN) ML was found. Conclusion: In predicting the severe postoperative complication among the bariatric surgery patients, ensemble algorithms outperform base algorithms. When compared to other ML algorithms, deep NN has the potential to improve the accuracy and it deserves further investigation. The oversampling technique should be considered in the context of imbalanced data where the number of the interested outcome is relatively small.

Background: The number of patients with myocardial infarction and severe obesity is increasing and there is a lack of evidence how these patients should be treated. The aim of this study was to investigate the association between metabolic surgery (Roux-en-Y gastric bypass and sleeve gastrectomy) and major adverse cardiovascular events in patients with previous myocardial infarction (MI) and severe obesity. Methods: Of 566 patients with previous MI registered in the SWEDEHEART registry (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) undergoing metabolic surgery and registered in the nationwide Scandinavian Obesity Surgery Registry, 509 patients (Roux-en-Y gastric bypass n=465; sleeve gastrectomy n=44) could be matched 1:1 to a control with MI from SWEDEHEART, but no subsequent metabolic surgery regarding sex, age (±3 years), year of MI (±3 years), and body mass index (±3). The 2 groups were well matched, except for a lower proportion of reduced ejection fraction after MI (7% versus 12%), previous heart failure (10% versus 19%), atrial fibrillation (6% versus 10%), and chronic obstructive pulmonary disease (4% versus 7%) in patients undergoing metabolic surgery. Results: The median (interquartile range) follow-up time was 4.6 (2.7–7.1) years. The 8-year cumulative probability of major adverse cardiovascular events was lower in patients undergoing metabolic surgery (18.7% [95% CI, 15.9–21.5%] versus 36.2% [33.2–39.3%], adjusted hazard ratio, 0.44 [95% CI, 0.32–0.61]). Patients undergoing metabolic surgery had also a lower risk of death (adjusted HR, 0.45 [95% CI, 0.29–0.70]; MI, 0.24 [0.14–0.41]) and new onset heart failure, but there were no significant differences regarding stroke (0.91 [0.38–2.20]) and new onset atrial fibrillation (0.56 [0.31–1.01]). Conclusions: In severely obese patients with previous MI, metabolic surgery is associated with a low risk for serious complications, lower risk of major adverse cardiovascular events, death, new MI, and new onset heart failure. These findings need to be confirmed in a randomized, controlled trial.

BackgroundFactors associated with risk for adverse outcome are important considerations in the preoperative assessment of patients for bariatric surgery. As yet, prediction models based on preoperative risk factors have not been able to predict adverse outcome sufficiently.ObjectiveThis study aimed to identify preoperative risk factors and to construct a risk prediction model based on these.MethodsPatients who underwent a bariatric surgical procedure in Sweden between 2010 and 2014 were identified from the Scandinavian Obesity Surgery Registry (SOReg). Associations between preoperative potential risk factors and severe postoperative complications were analysed using a logistic regression model. A multivariate model for risk prediction was created and validated in the SOReg for patients who underwent bariatric surgery in Sweden, 2015.ResultsRevision surgery (standardized OR 1.19, 95% confidence interval (CI) 1.14–0.24, p < 0.001), age (standardized OR 1.10, 95%CI 1.03–1.17, p = 0.007), low body mass index (standardized OR 0.89, 95%CI 0.82–0.98, p = 0.012), operation year (standardized OR 0.91, 95%CI 0.85–0.97, p = 0.003), waist circumference (standardized OR 1.09, 95%CI 1.00–1.19, p = 0.059), and dyspepsia/GERD (standardized OR 1.08, 95%CI 1.02–1.15, p = 0.007) were all associated with risk for severe postoperative complication and were included in the risk prediction model. Despite high specificity, the sensitivity of the model was low.ConclusionRevision surgery, high age, low BMI, large waist circumference, and dyspepsia/GERD were associated with an increased risk for severe postoperative complication. The prediction model based on these factors, however, had a sensitivity that was too low to predict risk in the individual patient case.

IntroductionPatients with high body mass index (BMI), pre-existing pain and young age and women seem to experience more postoperative pain. Few studies have, however, addressed these risk factors amongst obese patients undergoing bariatric surgery.The aim of the present study was to evaluate risk factors for postoperative pain following laparoscopic gastric bypass surgery.MethodsIn this cohort study, we used data from the PAIN OUT register for postoperative pain during the first 24 h after surgery. Primary outcome measure was severity of pain after surgery. Multivariate analyses were conducted to evaluate BMI, young age, gender and pre-existing pain as independent risk factors for postoperative pain.ResultsWe included 192 patients in this study. Younger age (B −0.08, 95%CI −0.11 to −0.05/year; p < 0.001), female gender (B 0.92, 95%CI 0.10–1.75; p = 0.029) and pre-existing pain (B 1.06, 95%CI 0.03–2.09; p = 0.044) were all associated with an increased risk for postoperative pain. In the multivariate analyses, only young age ((adjusted OR 0.95, 95%CI 0.92–0.97/year; p < 0.001) and pre-existing pain (adjusted OR 2.56, 95%CI 1.09–6.00; p = 0.031) remained as independent risk factors for severe postoperative pain.ConclusionYounger age and pre-existing pain are associated with severe postoperative pain during the first 24 h after laparoscopic gastric bypass surgery, whereas female gender and high BMI are not.