The burden of abdominal pain after bariatric surgery in terms of diagnostic testing: the OPERATE study.

BACKGROUND: Abdominal pain after bariatric surgery (BS) is frequently observed. Despite numerous diagnostic tests, the cause of abdominal pain is not always found. OBJECTIVES: To quantify type and number of diagnostic tests performed in patients with abdominal pain after BS and evaluate the burden and their yield in the diagnostic process. SETTING: A bariatric center in the Netherlands. METHODS: In this prospective study, we included patients who presented with abdominal pain after BS between December 1, 2020, and December 1, 2021. All diagnostic tests and reoperations performed during one episode of abdominal pain were scored using a standardized protocol. RESULTS: A total of 441 patients were included; 401 (90.9%) were female, median time after BS was 37.0 months (IQR, 11.0-66.0) and mean percentage total weight loss was 31.41 (SD, 10.53). In total, 715 diagnostic tests were performed, of which 355 were abdominal CT scans, 155 were ultrasounds, and 106 were gastroscopies. These tests yielded a possible explanation for the pain in 40.2% of CT scans, 45.3% of ultrasounds, and 34.7% of gastroscopies. The diagnoses of internal herniation, ileus, and nephrolithiasis generally required only 1 diagnostic test, whereas patients with anterior cutaneous nerve entrapment syndrome, irritable bowel syndrome, and constipation required several tests before diagnosis. Even after several negative tests, a diagnosis was still found in the subsequent test: 86.7% of patients with 5 or more tests had a definitive diagnoses. Reoperations were performed in 37.2% of patients. CONCLUSION: The diagnostic burden in patients with abdominal pain following BS is high. The most frequently performed diagnostic test is an abdominal CT scan, yielding the highest number of diagnoses in these patients.

Self-organized metabotyping of obese individuals identifies clusters responding differently to bariatric surgery.

Weight loss through bariatric surgery is efficient for treatment or prevention of obesity related diseases such as type 2 diabetes and cardiovascular disease. Long term weight loss response does, however, vary among patients undergoing surgery. Thus, it is difficult to identify predictive markers while most obese individuals have one or more comorbidities. To overcome such challenges, an in-depth multiple omics analyses including fasting peripheral plasma metabolome, fecal metagenome as well as liver, jejunum, and adipose tissue transcriptome were performed for 106 individuals undergoing bariatric surgery. Machine leaning was applied to explore the metabolic differences in individuals and evaluate if metabolism-based patients' stratification is related to their weight loss responses to bariatric surgery. Using Self-Organizing Maps (SOMs) to analyze the plasma metabolome, we identified five distinct metabotypes, which were differentially enriched for KEGG pathways related to immune functions, fatty acid metabolism, protein-signaling, and obesity pathogenesis. The gut metagenome of the most heavily medicated metabotypes, treated simultaneously for multiple cardiometabolic comorbidities, was significantly enriched in Prevotella and Lactobacillus species. This unbiased stratification into SOM-defined metabotypes identified signatures for each metabolic phenotype and we found that the different metabotypes respond differently to bariatric surgery in terms of weight loss after 12 months. An integrative framework that utilizes SOMs and omics integration was developed for stratifying a heterogeneous bariatric surgery cohort. The multiple omics datasets described in this study reveal that the metabotypes are characterized by a concrete metabolic status and different responses in weight loss and adipose tissue reduction over time. Our study thus opens a path to enable patient stratification and hereby allow for improved clinical treatments.

Pancreatic exocrine insufficiency after bariatric surgery.

BACKGROUND: Chronic abdominal complaints after bariatric surgery may be explained by pancreatic exocrine insufficiency (PEI). OBJECTIVES: We aimed to evaluate the clinical value of the Pancreatic Exocrine Insufficiency Questionnaire (PEI-Q) as a screening tool to identify patients with a high probability of having PEI. SETTING: Outpatient clinic for bariatric surgery. METHODS: Patients scheduled for a screening or follow-up appointment were asked to complete the PEI-Q and the Gastrointestinal Quality of Life Index questionnaire (GIQLI). Postoperative patients with a high PEI-Q score (0,6) were offered a fecalelastase (FE) test (abnormal if <200 µg/g). RESULTS: Between June 2020 and February 2021, a total of 1600 of 1629 PEI-Qs were completed, 1073 (67%) of which after surgery. The postoperative group consisted mostly of females (81.9%), aged 49.0 ± 10.6 years, with a total weight loss of 30.3% ± 8.8%. Among them, 63.4% had abnormal PEI-Q scores compared with 34.9% before surgery (P < .01). In contrast, the median GIQLI score increased (119 [interquartile range (IQR), 107-129.25] versus 110 [IQR, 95-121.75]) before surgery (P < .01). Additionally, 310 FE tests were performed, of which only 11.9% was suggestive of PEI. No correlation was found between the PEI-Q scores and FE levels (c-index .55). CONCLUSION: The PEI-Q in its current version is not able to distinguish complaints of PEI and bariatric surgery itself and therefore cannot be used as a screening tool for PEI. The specificity of the FE test seems to be reduced after surgery. Future research should include a more direct pancreatic function test, which may provide more insight into PEI after bariatric surgery.