Background: Bariatric surgery is an established treatment for severe obesity; however, fewer than 1 per cent of eligible patients undergo surgery. The perceived risk of surgery may contribute to the low uptake. The aim of this study was to determine perioperative mortality associated with bariatric surgery, comparing different operation types and data sources. Methods: A literature search of Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials was conducted to identify studies published between 1 January 2014 and 31 July 2020. Inclusion criteria were studies of at least 1000 patients reporting short-term mortality after bariatric surgery. Data were collected on RCTs. Meta-analysis was performed to establish overall mortality rates across different study types. The primary outcome measure was perioperative mortality. Different operation types were compared, along with study type, in subgroup analyses. The study was registered at PROSPERO (2019: CRD 42019131632). Results: Some 4356 articles were identified and 58 met the inclusion criteria. Data were available on over 3.6 million patients. There were 4707 deaths. Pooled analysis showed an overall mortality rate of 0.08 (95 per cent c.i. 0.06 to 0.10; 95 per cent prediction interval 0 to 0.21) per cent. In subgroup analysis, there was no statistically significant difference between overall, 30-day, 90-day or in-hospital mortality (P = 0.29). There was no significant difference in reported mortality for RCTs, large studies, national databases or registries (P = 0.60). The pooled mortality rates by procedure type in ascending order were: 0.03 per cent for gastric band, 0.05 per cent for sleeve gastrectomy, 0.09 per cent for one-anastomosis gastric bypass, 0.09 per cent for Roux-en-Y gastric bypass, and 0.41 per cent for duodenal switch (P < 0.001 between operations). Conclusion: Bariatric surgery is safe, with low reported perioperative mortality rates.

Bariatric, metabolic or weight loss surgery produces sustained weight loss and imporovement in obesity related diseases. Bariatric surgery has existed for decades but there is limited reliable data on the risk of perioperative mortality following the procedures. This commentary focuses on a recent meta-analysis which has produced contemporaneous mortality data, and the findings are significant. Utilising data from 3.6 million patients the study has shown an overall pooled perioperative mortality of 0.08%, a significantly reduced risk compared to previous, smaller studies. This finding increases our knowledge of surgical risk for these procedures and should now equip health care groups to challenge barriers to uptake of bariatric surgery. Barriers currently include a worldwide lack of focus on treating obesity, lack of funding and resource from commissioners, and a general public and professional view that bariatric surgery may be high risk. In reality, this figure equates to mortality risk for procedures generally considered 'safe' such as laparoscopic cholecystectomy and knee arthroplasty. Bariatric surgery is a safe option for achieving sustained weight-loss and the treatment of obesity related diseases, and refusing access to surgery on the grounds of perioperative safety should now be an outdated premise.

Background: Bariatric and Metabolic Surgery (BMS) is a popular weight loss intervention worldwide, yet few scientific studies have examined variations in preoperative practices globally. This study aimed to capture global variations in preoperative practices concerning patients planned for BMS. Methods: A 41-item questionnaire-based survey was designed and the survey link was freely distributed on social and scientific media platforms, email groups and circulated through personal connections of authors. The survey included eight parts: basic information; criteria for BMS; preoperative nutritional screening; preoperative weight loss; preoperative diets for liver size reduction; preoperative glycemic control; other laboratory investigations and preparations; decision making, education, and consents. Descriptive statistics were used to analyse data and graphs were used for representation where applicable. Results: Six hundred thirty-four bariatric healthcare professionals from 76 countries/regions completed the survey. Of these, n = 310 (48.9%) were from public hospitals, n = 466 (73.5%) were surgeons, and the rest were multidisciplinary professionals. More than half of respondents reported using local society/association guidelines in their practice (n = 310, 61.6%). The great majority of respondents routinely recommend nutritional screening preoperatively (n = 385, 77.5%), mandatory preoperative diets for liver size reduction (n = 220, 53.1%), routine screening for T2DM (n = 371, 90.7%), and mandate a glycemic control target before BMS in patients with T2DM (n = 203, 55.6%). However, less than half (n = 183, 43.9%) recommend mandatory preoperative weight loss to all patients. Most respondents (n = 296, 77.1%) recommend psychological intervention before surgery for patients diagnosed with psychological conditions. Variations were also identified in laboratory investigations and optimisation; and in the aspects of decision making, education and consent. Conclusions: This survey identified significant global variations in preoperative practices concerning patients seeking primary BMS. Our findings could facilitate future research for the determination of best practice in these areas of variations, and consensus-building to guide clinical practice while we wait for that evidence to emerge.