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

Clinical background for metabolic 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 produces the visible weight/BMI/waist circumference decrease (anthropometric measures), improvements in metabolic parameters and body composition studies *Metabolic bariatric surgery reduces systemic inflammation *Research studies reported significant improvements in composite inflammatory markers (SII, PIV, LMR) (see below) as well as traditional haematological parameters although at this stage there are no statistically significant relationship has been observed between weight loss, anthropometric measurements and inflammatory markers   Obesity related inflammation is not only dependent on adipose tissue but also other variables such as immune system activity, microbiota composition, hormonal balance, insulin sensitivity, individual genetic differences   Also dependent on dietary pattern changes, various level of physical activity and nutritional deficiency     Chronic low grade systemic inflammation plays a key role in the pathophysiology of obesity *Increased macrophage infiltration into adipose tissue triggers both local and systemic inflammation by release of pro-inflammatory cytokine *Adipose tissue (endocrine and paracrine organ) release hormones such as leptin, adiponectin and pro-inflammatory cytokines (TNFa, IL-6, IL-1B) *These cytokines lead to the development of metabolic disorders such as insulin resistance, endothelial dysfunction and oxidative stress   Translocation of lipopolysaccharides into the circulation through increased intestinal permeability and activation of the immune system via Toll like receptors 4 (TLR4) forms the immunological basis of the inflammatory process   New biomarkers of inflammation such as lymphocyte-monocyte ratio, neutrophil-lymphocyte ratio, platelet-lymphocyte ratio, systemic inflammation index (SII), pan immune inflammation value (PIV) as well as haemoglobin, albumin, lymphocyte and platelet (HALP) score help to evaluate the systemic inflammation burden   However measurements of biomarkers to evaluate the inflammation obesity relationship and body measurements are difficult to do objectively   Studies after sleeve gastrectomy has indicated that *there are significant changes in systemic inflammation markers in the post operative period with significant decreases in neutrophil, monocyte, platelet counts, reduction in SII and PIV scores *there are increases in lymphocyte count and LMR, inversely related to inflammation in the post operative period, decrease in PNI score and changes in HALP score   Meta-analysis reported that there is a decrease in CRP levels by 66%, IL-6 by 27% but no significant changes to TNF-a after surgery with 12-24 months follow up   The decrease in CRP begins within the first 3 to 6 months after surgery *A study reported decrease in leptin and TNF-a levels at 6 months after surgery *A study reported decrease in adiponectin for women at 12 months after gastric bypass together with significant decrease in CRP and IL6   The modified mHALP scores can be used as a significant predictor for weight loss and improvement in body composition or to predict whether the %EWL will be remain below 60%   High pre-op glucose to lymphocyte ratio value were found to be associated with increase lean muscle mass and total body water   High PNI was negatively correlated to changes in fat mass, lean mass, total body water and muscle mass

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