Erik Stenberg

INTRODUCTION: Type 2 diabetes (T2D) and obesity are among the most important risk factors for dementia. Although weight loss is an important preventive strategy, the impact of metabolic and bariatric surgery (MBS) on dementia risk remains contradictory. METHODS: We conducted a propensity score matched study using nationwide, high‐quality clinical registries to compare the outcomes in patients with obesity and T2D who underwent MBS with matched controls who did not undergo surgery. RESULTS: Over a mean follow‐up of 9 years, MBS was associated with a reduced risk of dementia (15‐year cumulative incidence 1.8% vs. 2.7%, subdistribution hazard ratio [SHR] 0.60, 95% CI 0.47–0.76). The incidence was lower for Alzheimer's disease (1.2% vs. 1.9%, SHR 0.56, 95% CI 0.41–0.76) and vascular dementia (0.4% vs. 0.7%, SHR 0.49, 95% CI 0.29–0.85), but increased for alcohol‐related dementia (0.2% vs. 0.04%, SHR 3.67, 95%CI 1.33–10.14). DISCUSSION: These findings suggest that the collected long‐term effects of MBS may reduce the risk of developing dementia in individuals with obesity and T2D.

Background: Predicting postoperative body mass index (BMI) trajectories and long-term type 2 diabetes (T2D) remission after bariatric surgery remains challenging. Existing models often rely on baseline variables only and fail to incorporate dynamic postoperative changes. This study aimed to develop and validate a multicentre machine-learning framework that predicts individualized BMI trajectories and T2D remission using routinely available preoperative data and time-dependent weight evolution. Methods: This multicentre retrospective cohort study included adult patients who underwent Roux-en-Y gastric bypass or sleeve gastrectomy across 11 European centres (2012–2023). Variables with > 30% missing data were excluded; remaining missing values were imputed iteratively. A two-stage approach was used: a regression model predicting postoperative BMI at 3–60 months using an autoregressive design; and a classification model predicting T2D remission using baseline features and predicted BMI trajectories. Internal performance was evaluated with ten-fold and leave-one-clinic-out cross-validation; external validation used an independent cohort from Linköping, Sweden. Results: Of the 11 457 patients initially identified, 9652 patients with complete baseline and follow-up information were used for the analysis. The best BMI model (HistGradientBoosting) achieved a root mean square error (RMSE) of 1.11 kg/m2 (95% confidence interval 1.07 to 1.14) and a mean absolute error (MAE) of 0.62 kg/m2 across clinics; external testing showed an RMSE of 1.12 kg/m2 (95% confidence interval 1.11 to 1.12) and an MAE of 0.63 kg/m2. The T2D remission classifier (XGBoost) obtained a Macro F1 score of 0.88 (precision 0.87, recall 0.88), with an external F1 score of 0.89. Incorporating predicted BMI trajectories improved discrimination compared with baseline-only models (C-index 0.95 versus 0.93). Conclusion: A two-stage machine-learning framework has high predictive performance for postoperative BMI and T2D remission up to 5 years after bariatric surgery. Dynamic incorporation of predicted weight trajectories enhances metabolic risk prediction and supports individualized counselling and postoperative management.

Background: Metabolic-bariatric surgery is an efficient therapy in selected adolescents with severe obesity. However, predicting the postoperative weight loss is challenging. A machine learning calculator predicting 5-year weight loss trajectory has been developed in adults, based on seven preoperative features. The aim of the present study was to adapt and test it in adolescents. Methods: Retrospective cohort study in patients aged 12–20 years undergoing Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), or adjustable gastric band (AGB) in France and Sweden between 2001 and 2022. Primary outcome was the accuracy of 5-year BMI prediction, expressed as the median absolute deviation (MAD) between predicted and observed BMI. The model developed in adults, was trained in a subset of 80% of randomly selected adolescents, and secondly tested in the remaining 20%. Results: We enrolled a total of 2255 patients (1705 female [75.6%], 12–20 years [median 19]). Five-year follow-up data were available for 59% of French and 38% of Swedish patients. The median (IQR) 5-year total weight loss was 30.2% (23.9–38.6) for RYGB, 23.4% (13.7–32.8) for SG, and 13.4% (0.0–30.1) for AGB. The adapted model predicted the observed 5-year BMI with a MAD of 3.7 kg/m² (95% CI [3.3–3.9]). The accuracy of the model was maximal for bypass (3.2 kg/m² [3.0–3.7]), good for SG (3.9 kg/m² [3.1–5.0]), and lower for AGB (7.3 kg/m² [5.5–8.4]), and accuracy decreased with time and in adolescents under 19 years. Age, height, weight, and type of intervention influenced 5-year weight loss. Type 2 diabetes influenced weight loss until 2 years after surgery, but not later. Conclusion: The model had an acceptable accuracy for adolescents to predict 5-year postoperative weight loss trajectory. Accuracy decreased over time and was influenced by type of intervention and age. This calculator is available online: https://bariatric-weight-trajectory-prediction.univ-lille.fr/ .

Background/objectives: Studies show equal or better resolution of type 2 diabetes mellitus (T2D) and other metabolic outcomes after Roux-en-Y gastric bypass (RYGB) compared to sleeve gastrectomy (SG), but it is unclear whether this is related only to the higher weight loss after RYGB, or if there are weight-loss-independent factors. The objective of this study was to examine weight-loss-independent differences in metabolic outcomes between RYGB and SG. Methods: This study utilized the Scandinavian Obesity Surgery Registry and the Swedish National Diabetes Register. All included patients had presurgical T2D and matching was between RYGB or SG using a 1:1 propensity score, matching with a generalized linear model including age, sex, BMI at baseline, comorbidities (cardiovascular, dyslipidemia, sleep apnea, and hypertension), T2D parameters at baseline (HbA1c, number of T2D medications, insulin use, duration of T2D), year of surgery and percentage Total Weight Loss (%TWL) at nadir. The ensuing cohort was compared regarding remission and improvements in T2D, and other cardiometabolic outcomes, including major adverse cardiovascular events (MACE). Results: 1440 individuals (720 RYGB; 720 SG) were matched 1:1 using Propensity score. There were 494 (68.6%) patients in complete T2D remission at 2 years after RYGB, and 438 (60.8%) after SG, (OR: 0.75, 95% CI 0.60 – 0.93, p = 0.010) despite similar TWL (Standardized mean difference 0.12). SG also had a lower rate of pharmacological remission for T2D (OR 0.71, 95% CI 0.56-0.88, p = 0.002), and hypertension remission (OR 0.70, 95% CI 0.52-0.94, p = 0.019), but there was no significant difference in pharmacological remission regarding dyslipidemia (OR 0.83, 95%CI 0.66-01.04, p = 0.11). No difference was seen in the risk for MACE (SG vs. RYGB HR:1.45, 95%CI 0.89-2.38, p = 0.136). Conclusions: RYGB is associated with a greater rate of T2D remission compared to SG. This study suggests that these improved outcomes are independent of the degree of weight loss.

Patients with initial body mass index > 50 kg/m² are vastly under-represented in randomized clinical trials demonstrating similar weight loss and diabetes remission rates after sleeve gastrectomy and Roux-en-Y gastric bypass. Propensity score matching 1 : 1 was used to compare outcomes regarding weight loss and diabetes control after sleeve gastrectomy and Roux-en-Y gastric bypass in patients with body mass index > 50 kg/m² between 2012 and 2022 in a cohort from 13 centres in six European countries. The primary endpoint was percentage total bodyweight loss; secondary endpoints were diabetes remission rate and rate of persistent body mass index > 40 kg/m². In total, 3976 of 8160 patients were matched and included in the analysis (1988 in each group). Median age at baseline was 40.0 (range 16–76) years in the sleeve gastrectomy group and 39.5 (15–71) years in the Roux-en-Y gastric bypass group. Median body mass index at baseline was 56.2 (range 50.0–100.0) and 54.3 (50.0–83.9) kg/m², respectively (P < 0.001). The follow-up rate was 70.5% at 1 year and 24.4% at 5 years. Percentage total bodyweight loss at 1 and 5 years after sleeve gastrectomy was 30.2 (2.2–63.7) and 25.4 (–4.8 to 56.0)%, respectively, versus 31.2 (7.4–54.5) and 28.2 (−6.6 to 62.9)% in the Roux-en-Y gastric bypass group (P < 0.001 between groups in both time points). The prevalence of persistent body mass index > 40 kg/m² after 1 and 5 years was 42.7 and 57.6%, respectively, after sleeve gastrectomy versus 24.5 and 39.2% after Roux-en-Y gastric bypass (P < 0.001 between groups in both time points). A 5-year follow-up, the prevalence of a pathological haemoglobin A1c level (> 6.5%) was 12.9% after sleeve gastrectomy and 11.6% after Roux-en-Y gastric bypass (P = 0.323). This study suggests that Roux-en-Y gastric bypass results in greater weight loss than sleeve gastrectomy in patients with body mass index > 50 kg/m², whereas improvements in diabetes appear comparable between procedures.

Social anxiety disorder is common among patients considered for metabolic and bariatric surgery (MBS). The combination of social anxiety with obesity may, however, be associated with a higher risk for adverse outcomes after surgery. In this nationwide, registry-based, matched cohort study, all patients who underwent primary MBS in Sweden from 2007 until 2019 and who had a diagnosis of moderate to severe social anxiety disorder (n = 586) were matched using a Propensity score to controls who underwent the same treatment but who did not have social anxiety disorder (n = 5791) with a mean follow-up time of 6.9 years. Patients with social anxiety disorder experienced an increased risk for non-serious postoperative complications (OR 1.59; 95%CI 1.21–2.09), self-harm (HR 2.44 CI 95% 1.84–3.25 p < 0.001) and alcohol or substance abuse (HR 2.41, 95%CI 1.96–2.96, p < 0.001), and reported lower psychosocial health-related quality of life before and after surgery. However, patients with social anxiety disorder significantly improved in health-related quality of life compared to baseline, and experienced similar effects on weight reduction at 2 years after surgery (total weight loss: 32.8 ± 10.3% compared to 32.6 ± 9.7%) and risks for cardiovascular events compared to the matched control group. MBS appears to be a safe and effective treatment for severe obesity in patients with social anxiety disorder, but an individualized and increased peri- and postoperative support should be considered for patients with moderate to severe social anxiety disorder and severe obesity.

Background With over 1 billion individuals affected globally, obesity and obesity related diseases is now a leading cause of death. Metabolic and bariatric surgery (MBS) has emerged as a cornerstone intervention for severe obesity and its associated comorbidities. Despite its efficacy, postoperative care and follow-up after MBS remains highly variable worldwide. Objective The PARTNER study aimed to evaluate global clinical practices in the postoperative management following MBS by surveying multidisciplinary healthcare professionals. Methods This study was an international online survey conducted between October 2024 and January 2025. A multidisciplinary team developed the questionnaire based on existing literature and international guidelines. The survey assessed five domains: follow-up care, postoperative treatment, dietary management, patient support, and measurement of surgical outcomes. Responses were analysed descriptively. Results A total of 262 responses were received from 62 countries. Most respondents were bariatric surgeons (72.1%) working in public healthcare systems (73.3%). While 78.7% reported conducting three-month postoperative reviews, only 23.7% offered indefinite follow-up. Hybrid models of care (virtual and in-person) were common (56.9%). VTE prophylaxis and postoperative PPI use were recommended by 64.1% and 84.3% respectively. Nearly all respondents (98.1%) provided dietary advice, with protein and micronutrient supplementation widely endorsed. Only 56.1% routinely referred patients for psychological follow-up. Definitions of surgical success and failure varied widely, with inconsistent objective outcome measures. Conclusion The PARTNER study reveals significant international variation in postoperative management practices following MBS. These findings underscore the need for more standardized, evidence-based guidelines to improve long-term outcomes and equity of care worldwide.