Prospective Randomized Study Comparing Three Hypoabsortive Techniques for the Treatment of Type IV Obesity: Double-anastomosis Duodenal Switch (DS), Single- Anastomosis Duodenal Switch SADI-S) and One Anastomosis Gastric By-pass (OAGBP)

Morbid obesity is the first non-traumatic cause of death in the western population and it is also progressively beginning to affect the developing countries. Bariatric surgery provides better results than pharmacological treatments and lifestyle changes, granting a better control of comorbidities.

Duodenal switch (DS) has shown to be the most effective surgical treatment for morbid obesity and its comorbidities. However, it is not widely used due to its technical complexity and the risk of long-term complications. In 2007 Drs. Sánchez-Pernaute and Torres introduced a simplified version of the DS technique: Single Anastomosis Duodenum-Ileal bypass with Sleeve gastrectomy (SADI-S). SADI-S consists of a vertical gastrectomy (VG) and a duodenum-ileal anastomosis preserving the pylorus with jejunal exclusion and a total common-alimentary loop originally of 200 cm and later standardized to 300 cm to reduce the risk of nutritional deficits. In order to diminish the surgical time and postoperative risks an omega reconstruction is performed without an ileo-ileal anastomosis. SADI-S can be performed either directly as primary surgery, planned in two stages, or as revisional surgery in case of insufficient weight loss or weight regain after VG. In terms of weight loss and comorbidity resolution, SADI-S' reported results are similar to those reported in historical DS series, but no prospective comparative studies have been published.

Recently, another simplified hypo-absorptive technique has started to be widely used: the one anastomosis gastric bypass (OAGBP), also called mini-gastric gypass. It consists of a gastric pouch associated with a gastro-jejunal anastomosis (Billroth II). It was initially described by R. Rutledge in 1997 and despite its first publication was in 2001, only lately it has been approved as a standard bariatric technique. OAGBP with a 200 cm biliopancreatic limb has shown good results in weight loss and control of comorbidities, higher than those achieved by VG and proximal Roux-en-Y gastric bypass (RYGBP) with 50 cm biliopancreatic limb and 150 cm alimentary limb, as it has been demonstrated in two prospective randomized studies and a recent meta-analysis. However, the OAGB results have not been compared with other hypo absorptive surgical techniques, such as DS or SADI-S.

In comparison to the DS, which has a Y-Roux reconstruction, SADI-s and OAGBP have a "Billroth II-like" or omega reconstruction. Despite the potential advantages of these emerging surgical techniques, bile reflux is the main issue of omega reconstructions. In our most recently published series including 440 consecutive patients, we reported that 1.7% of patients required conversion to DS due to symptomatic bile reflux. It would be reasonable to expect higher incidence of bile reflux in techniques with omega reconstruction that do not preserve the pyloric barrier, such as OAGBP. However, some authors claim that with a 200 cm biliopancreatic limb most of the bile is reabsorbed by the intestine before it reaches the gastro-jejunal anastomosis. This would minimize bile reflux in comparison to the historical series of Billroth II reconstruction after gastrectomy for oncological or peptic disease (in which the biliopancreatic loop is much shorter, generally around 50 cm). Reported incidences of symptomatic bile reflux after OAGBP vary between 0.5% and 1.5%, comparable to our SAID-S results. It is worth mentioning that not all bile refluxes are symptomatic and that biliary gastritis is a premalignant condition. At present, there is a lack of literature on acid and bile reflux after bariatric surgery comparing the 3 digestive reconstruction techniques: (i) Roux-en-Y with pyloric preservation (DS), (ii) omega reconstruction with pyloric preservation or "Billroth II-like" (SADI-S) and (iii) omega reconstruction without pyloric preservations or Billroth II (OAGBP).

This prospective randomized study aims to compare conventional DS with SADI-S and OAGBP. We include all morbidly obese patients with BMI ≥ 50 kg/m2 and candidates to a directly DS following our treatment algorithm. Exclusion criteria are patients who do not fulfill our preoperative bariatric assessment for surgery and those with contraindications for hypo absorptive or mixed surgery.