Primary sleeve gastrectomy Summary of clinical data and statistics   The primary sleeve gastrectomy is still the most commonly performed procedure worldwide, with good efficacy after 2 decades *However in the long term there may be 10-40% weight regain or inadequate weight loss *30-60% develop worsening pre-existing reflux or new de novo reflux *11-22% people have revision/conversion surgery after a primary sleeve *5-15% people have revision/conversion surgery because of weight regain due to retained posterior gastric fundic pouch or sleeve dilatation (for a re-sleeve)     The primary sleeve gastrectomy is still the safest primary metabolic bariatric procedure worldwide, with the best safety outcomes after 2 decades     The primary sleeve gastrectomy is the best option for many people either as a definitive weight loss procedure or as a planned staged procedure in the future *Long term limitation of a sleeve gastrectomy in terms of weight loss durability and development of reflux helps determine the need for revision/conversion procedures ***Weight regain has been reported between 5.7 to 39.5% of patients within 6 years   All revision/conversion metabolic bariatric surgery is associated with a higher risk of post operative complications   The decision to undergo complex gastric bypass, SADI-S or DS should not be taken lightly

Re-sleeve gastrectomy   The re-sleeve is much more difficult to do than the primary sleeve due to alteration of the gastric anatomy, especially with a hiatus hernia, mediastinal fibrosis, posterior gastric adhesions, reduced blood supply, etc *It is associated with 2.5X higher complication rates from leak, infection/sepsis and re-operation rate *the efficacy of treating reflux remains uncertain *some re-sleeve cases ended up having a gastric bypass eventually especially for reflux issues due to impaired gastric motility, raised intra gastric luminal pressure and constant exposure to acid/bile contents   The re-sleeve does have a role in carefully selected patients for patients without reflux issues for isolated sleeve dilatation and because of patient preferences (the desire to avoid the gastric bypass)

Sleeve to Roux Y gastric bypass   The most common is conversion procedure is from sleeve to Roux Y gastric bypass because of reflux (with or without hiatus hernia or stenosis near the incisura) +/- weight regain   Some studies reported significant reflux symptom resolution and favourable weight loss outcomes with acceptable morbidity rates and low complication rates of RYGBP compared to re-sleeve (data below)   One meta-analyses reported *Conversion to RYGBP is performed for reflux (30.4% of cases) and insufficient weight loss/weight regain (52% of cases) *Weight loss result is about 22.8% (after 1 year) with a 16.4% 30 day complication rate   Another study reported 53.9% excess weight loss at 1 year, 53% T2DM remission rates and complication rates 8.2% after conversion to RYGBP

Sleeve to OAGB, DS and SADI-S   There are other options such as conversion from sleeve to one anastomosis gastric bypass, SADI-S and duodenal switch (DS)   Some studies reported: *OAGB has superior weight loss results (with 83.6% EWL) than re-sleeve (60.3% EWL) or RYGBP *But a re-sleeve has a higher risk of worsening reflux or new onset reflux   A meta-analysis reported DS and SADI-S provide the most substantial weight loss (28.4 vs 21.1 % EWL at 1 and 3 years) with the highest resolution of obesity related co-morbidities but also carries the highest risk for nutritional deficiencies and future surgical complications   SADI-S has slightly better results than OAGB (19.1 vs 13.1% %EWL at 3 years)   Current evidence suggested that OAGB or RYGBP are preferable than a re-sleeve or the other malabsorptive procedures, because of efficacy, safety and long term benefits with less complications in the revision/conversion scenarios

General background information for bariatric surgery   Sleeve gastrectomy remains the most popular primary metabolic and bariatric procedure worldwide   The widespread adoption is due to the favourable safety profile, technical simplicity and effectiveness in promoting weight loss and resolution of medical co-morbidities   As a primary procedure it can achieve up to 29.5% TWL after the first year   But there is also a higher rate for revisional surgery after a sleeve gastrectomy for 2 main reasons: *Inadequate weight loss or weight regain *Hiatus hernia and gastro-oesophageal reflux   Sleeve gastrectomy conversion to Roux Y gastric bypass is the standard recommendation for reflux and may offer limited or modest additional weight loss *However please note there is no guarantee that converting to RYGBP will eliminate all the reflux symptoms, result in much more weight loss or remission of metabolic diseases   As described below many other factors should be addressed before rushing into revisional or conversion surgery *Bear in mind metabolic bariatric surgery is about making positive lifestyle changes and improvements in health, it is not just about the body scales or numbers (kg or BMI)   Some patients regret changing the sleeve to a bypass because of *loss of restriction *extensive follow up (multivitamin supplements, multiple blood tests, iron infusion, vitamin injections) *increase risk of side effects (dumping/diarrhoea) *increase complications and further revision surgery needed (gastric ulcer, internal hernia, small bowel obstruction) *severe diarrhoea or malnutrition requiring reversal of the gastric bypass

Inadequate/suboptimal clinical response and weight gain recurrence   Metabolic bariatric surgery is very effective for treating severe obesity and its associated medical co-morbidities   However 10-20% patients experience suboptimal clinical response and 20-35% experience weight gain recurrence   This is often multifactorial which include medical conditions, dietary non-adherence, maladaptive eating behaviour, physical inactivity, mental health issues and surgical/technical factors   Factors to consider include: *Homeostatic hunger is triggered by food deprivation (mediated by the vagus nerve and gut hormones) and microbiota driven hunger (modulated by alterations in gut hormones) *Hedonic hunger is driven by the pleasure of eating rather than metabolic need, over riding the hypothalamic control of energy balance, resulting in consumption of high fat, high sugar foods *Psychological factors such as anxiety, depression and maladaptive eating behaviours are significant contributors to suboptimal clinical response or recurrent weight gain after surgery *Emotional eating, lack of mindful eating, poor sleep and psychiatric disorders (binge eating, bulimia, impulsive eating) are strongly associated with weight regain   Inadequate weight loss or weight regain should not be interpreted as surgical failure but points to the fact that surgical therapy alone is not the solution and additional management strategies are needed, especially lifestyle modification and obesity management medications (OMM) as well as the input psychiatric treatment are necessary   Growing evidence suggests that OMM can increase the weight loss outcomes after metabolic bariatric surgery within the first year of surgery *OMM include liraglutide, semaglutide, phentermine, topiramate, lorcaserin or naltrexone/bupropion slow release (Contrave) *Contrave is beneficial with stress induced or craving triggered eating patterns *GLP-1 RA agonist is beneficial especially for patients who need additional metabolic benefits, eg. patients with T2DM To address the above issues patients are recommended to visit their dietitian, psychologist, general practitioners and endocrinologist

Disadvantages of metabolic bariatric surgery   There are *Direct technical or surgical complications include staple line or anastomotic leak, marginal ulcer, stricture, hiatus hernia, internal hernia, small bowel obstruction *Or other indirect related issues such as gallstones and kidney stones   In the longer term there may be micronutrient deficiencies especially iron, calcium, vitamin D, vitamin B12 and B9 (folate)   Following MBS patient needs to adhere to post op diet by having a high protein diet and avoiding fat-sugar meals *Non compliance may lead to inadequate weight loss or rapid weight gain recurrence   Regular physical activity is recommended to preserve lean muscle mass, improving core strength/balance and preventing bone demineralization/osteoporosis       Please note: *Weight gain recurrence is common and may occur with all types of MBS, this is not a surgical/patient failure *One systematic review reported 17.6% patients experience weight regain of about 10% of the lost weight * However the focus is not just about the weight loss, please read the important information below about the benefits of metabolic bariatric surgery beyond weight loss         Causes of weight regain includes: *Technical reasons such as greater gastric capacity or expanded gastro-jejunal stoma diameter *Dietary practices such as emotional eating behaviour, excessive sugar intake and mental health condition (anxiety, depression) *Genetic predisposition/variations, slower metabolism, slower patient recovery   Hence personalized medicine, nutrition and maybe in the future genomics study will help tailor the best pathway to combat individual obesity and metabolic problems *Tailor meal plans according to lifestyle, metabolic and genetic variables also to maximise nutrition absorption *Individualised pharmacotherapy or patient specific technology/intervention may help to significantly improve weight loss and ensure sustained weight loss, improve health related quality of life and reduce complications

Clinical background for metabolic bariatric surgery Beyond weight loss, it is not just about kg or BMI loss   Patients with obesity are also a metabolically heterogenous group Metabolic bariatric surgery (MBS) * produces the significant weight/BMI/waist circumference decrease (anthropometric measures) and body composition changes * affects gut hormone secretion (GLP-1, ghrelin, leptin, etc) which helps influence appetite control, energy balance, nutrient absorption, glucose metabolism, lipid metabolism and fat storage * reduces systemic inflammation * has significant cardio-vascular benefits * alters bile acid metabolism and gut microbiome Note: 1. MBS has much more beneficial effects beyond just alterations in surgical anatomy (restriction or hyperabsorption/malabsorption) 2. MBS has major impact on metabolism and the body’s physiological process beyond weight loss The physiology changes after MBS * supporting the foregut and hundgut hypothesis, ileal brake and gastric centre hypothesis * influences the gut brain axis, cognitive improvements and better eating habits This is termed “The benefits of metabolic bariatric surgery beyond weight loss”

Summary

The decision to have a primary sleeve gastrectomy is a shared decision between the medical and allied health team together with the patient and their family/support system

Patients should be fully informed of the benefits, advantages, disadvantages, side effects, risk and complications of the different types of primary and revision/conversion metabolic bariatric surgery

The decision to undergo metabolic bariatric surgery is beyond clinically significant weight loss (>20% TWL) alone, for example:

• To achieve control or remission of obesity related metabolic or cardio-vascular risk factors
• For improvements in health related quality of life
• Reduce chronic inflammation and chronic diseases
• Reduce long term complications and premature cardio-vascular and all cause related mortality

Patients are encouraged to do more research before deciding on surgery, to discuss all the above carefully with their family members or people in their supportive circle as well as their general practitioners, physicians, surgeons, allied health team, employers and other relevant parties

Revision/conversion surgery may or may not add further significant weight loss, eliminate the reflux or metabolic medical co-morbidities and carries with it a higher post op complication rate