Are objections to one anastomosis/mini gastric bypass scientific?

Dear Editor,

Many thanks for giving us the opportunity to respond to this anonymous letter written in response to our article published in your esteemed journal.[1] Although One Anastomosis/Mini Gastric Bypass (OAGB/MGB) has a definite complication rate, it is probably lower than the Roux-en-Y gastric bypass (RYGB).[23] Many OAGB/MGB surgeons have privately told me that a complication than can be managed conservatively or with a bit of patience is often treated with a reoperation by other surgeons. Since I work in the National Health Service where there is no financial motive, I do not personally face this problem. Our unit is routinely involved in the care of our patients who present to the neighbouring centres with a complication. When Johnson et al. reoperated these patients, it would be worth knowing, if they did the same especially because they do not themselves perform this procedure and are unlikely to have had a huge experience in dealing with these patients.[4]

I recognise the scarcity of studies evaluating gastro-oesophageal reflux disease (GORD) after this procedure, but I do not believe we can ever power a study with a neoplasm as an end point, especially since not a single case of the gastric pouch or oesophageal cancer has yet been reported in scientific literature. We have addressed this issue in detail in our article.[1]

There is currently a lack of evidence to preclude patients with pre-existing GORD from OAGB/MGB, once again pointing to the lack of studies I mentioned above. I would be interested to see the results of OAGB/MGB in these patients in comparison with, for example, sleeve gastrectomy. Similarly, we have previously examined[5] in some detail, the consequence of bile reflux into the stomach and oesophagus and do not believe there is sufficient evidence in the scientific literature to label bile as a carcinogen. Even if, and this does remain unproven, this procedure was associated with a higher incidence of gastritis, we cannot assume that it will result in a higher incidence of dyspeptic symptoms and/or gastric cancers.

The study by Csendes et al.[6] cannot be used to suggest what would happen after OAGB/MGB as the remnant stomach left after a distal gastrectomy has a different configuration to a long and narrow OAGB/MGB pouch. This is indeed reminiscent of Mason's loop bypass and OAGB/MGB surgeons are always keen to stress the construction of a longest possible tube that a patient's stomach would allow to minimise oesophageal exposure to enteric content. Similarly, all Macdonald and Owen[7] showed was that gastric cancer post-ulcer surgery had different histological characteristics to gastric cancer in patients without prior gastric cancer surgery. I do not believe that we can read much more from this retrospective study with very small numbers that includes patients after a variety of post-ulcer surgery and includes patients as far back as 1975 when we did not know the importance of Helicobacter pylori in this disease.

The fact that not a single gastric pouch or oesophageal cancer has been reported in the scientific literature would indeed make any suggestion of regular surveillance endoscopy unethical. Indeed, I do not believe this to be a major problem after any bariatric surgery and despite the fact that cancers have been reported after bariatric surgery, the overall effect of bariatric surgery is to reduce cancers not increase it.

I have stressed before[8] that neither RYGB nor OAGB/MGB are malabsorptive procedures. Gastric bypass patients and this is true of both types of bypasses, consume far fewer calories and hence by implication also a lower than recommended amount of protein during the 1st year after surgery but in the long-term, when the weight reaches a plateau stage, they can consume adequate amounts of protein. We do not routinely recommend protein supplements to our patients, even those who are vegetarians. It is worth mentioning in this context that proximal gastric bypass behaves differently to distal gastric bypass. OAGB/MGB with 150 cm biliopancreatic limb is a proximal gastric bypass, and these patients experience little malabsorption. Longer limb OAGB/MGB, just like distal variations of RYGB, will result in a higher incidence of protein-calorie malnutrition without any clinically significant gains in terms of weight loss. I further challenge the authors’ interpretation of the study by Luger et al.[9] Even though Luger et al.[9] used a biliopancreatic limb of 200–220 cm, they did not find any significant difference in albumin levels postoperatively at 3, 6 months and 1 year compared to pre-operative values. Remarkably, authors found that 8.3% of patients had suboptimal albumin levels at 1 year compared to 8.2% preoperatively.

Finally, I agree that patients have a right to know that some surgeons believe this procedure would be associated with a higher risk of gastric and/or oesophageal cancer, but patients also have a right to know that there is no evidence till date to link this procedure with these cancers. Indeed, as I have argued before,[10] we have not observed a higher incidence of gastric pouch and/or oesophageal cancers after Mason's loop gastric bypasses either, which one could reasonably expect to result in a higher risk of bile reflux into the oesophagus. However, if patients have to be informed adequately, we should perhaps also share with them that studies show lower complication rate and/or higher weight loss with OAGB/MGB in comparison with RYGB and sleeve gastrectomy.[231112] It would also be worth sharing with patients that this operation has a longer track record that now spans almost 20 years compared to some other younger procedures that are now mainstream.

Finally, when it comes to endorsement by national societies, it is the responsibility of office holders to declare their position clearly and if in the case of OAGB/MGB, their position is that this procedure cannot be recommended for introduction into the mainstream, I would only suggest that they transparently share their views with the community and authors of the position statement suggest what would be required before this procedure, with many apparent advantages, can be inducted into the mainstream. It would be further useful to have authors listed clearly just as we would in any scientific exchange for future accountability of these decisions. This is all the more important considering OAGB/MGB now meets most of the requirements that bariatric community would like to see in a new bariatric procedure before it can be included as a mainstream procedure.[13]

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Conflicts of interest

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