# Efficiency and safety of one anastomosis gastric bypass vs Roux-en-Y gastric bypass: a real-life study

Lea Pietri, Florian Mourre, Bruno Berthet, Julien Mancini, Audrey Bégu-Le Corroller, Marie Maraninchi, René Valero

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Lea Pietri, Florian Mourre, Bruno Berthet, Julien Mancini, Audrey Bégu-Le Corroller, et al. Effi- ciency and safety of one anastomosis gastric bypass vs Roux-en-Y gastric bypass: a real-life study. Journal of Gastrointestinal Surgery, 2025, 29 (6), pp.102050. 10.1016/j.gassur.2025.102050. inserm- 05080093

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Pietri L, Mourre F, Berthet B, Mancini J, Corroller AB, Maraninchi M, Valero R. Efficiency and

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safety of one anastomosis gastric bypass vs Roux-en-Y gastric bypass: a real-life study. J

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Gastrointest Surg. 2025 Jun;29(6):102050. doi: 10.1016/j.gassur.2025.102050. Epub 2025 Apr

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2. PMID: 40185306.

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EFFICIENCY AND SAFETY OF ONE ANASTOMOTIC GASTRIC BYPASS
VERSUS ROUX-EN-Y GASTRIC BYPASS: A REAL LIFE STUDY

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Lea Pietri¹, Florian Mourre¹, Bruno Berthet², Julien Mancini³, Jeanine Dupont¹, Audrey Bégu-

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Le Corroller¹, Juan Patricio Nogueira⁴,⁵, Noémie Dubois¹, Rachel Grangeot¹, Sophie Béliard¹,

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Marie Maraninchi* ☉, ¹, René Valero*, ¹

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¹ Aix Marseille Univ, APHM, INSERM, INRAE, C2VN, University Hospital La Conception,

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Department of Nutrition, Metabolic Diseases and Endocrinology, 147 boulevard Baille, 13005

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Marseille, France

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² APHM, Department of General and Endocrine Surgery, University Hospital La Conception,

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147 boulevard Baille, 13005 Marseille, France

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³ Aix-Marseille Univ, INSERM, IRD, UMR1252, SESSTIM, Marseille, F-13273, France and

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APHM, Timone Hospital, Public Health Department (BIOSTIC), Marseille, F-13385, France

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⁴ Docencia e Investigacion, Hospital Central de Formosa, CP 3600, Salta 555, Formosa,

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Argentina

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⁵ Facultad de Ciencias de la Salud, Universidad Nacional de Formosa, Gutnisky 3200, CP 3600,

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Formosa, Argentina

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* René Valéro and Marie Maraninchi contributed equally to this work.
24 **Correspondance** to Marie Maraninchi, Ph.D, Service de Nutrition, Maladies métaboliques et Endocrinologie, Centre hospitalo-Universitaire de La Conception, 147 Boulevard Baille, 25 13005 Marseille, France. Fax number: (+33)4 91 38 41 32, Phone number: (+33)4 91 38 36 50. 26
E-mail: marie.maraninchi@univ-amu.fr 27

28 **Conflict of interest:** The authors declare that they have no conflict of interest.

29 **Funding:** none

30 **Running title:** Comparison of 2 gastric bypass

31 **Main text word count:** 3540

32 **Abbreviations:** BMI, body mass index; EWL, excess weight loss; HbA1C, glycated hemoglobin; HDL-c, high density lipoprotein-cholesterol; HOMA-IR, homeostasis model assessment-insulin resistance; LDL-c, low density lipoprotein-cholesterol; OAGB, one anastomosis gastric bypass; OSAS, obstructive sleep apnea syndrome; RYGB, Roux-en-Y gastric bypass; TWL, total weight loss; WHO, World health organization.
37 **ABSTRACT**

38 **Background/Objectives:** Use of bariatric surgery has greatly increased recently due to its
39 effectiveness in treating morbid obesity. Beside Roux-en-Y gastric bypass (RYGB) gold
40 standard technique, a modified technique, the one anastomosis gastric bypass (OAGB), has
41 recently been developed, but is not accepted worldwide and remains a controversial procedure.

42 We compared short-term efficacy and safety outcomes of OAGB versus RYGB (Setting:
43 University public hospital, France).

44 **Subjects/Methods:** Ninety-five patients with obesity undergoing OAGB (n=45) or RYGB (n=50) surgery were consecutively included. Clinical, surgical, biochemical, nutritional and body composition parameters were evaluated 1 month before and 12 months after surgery.

47 **Results:** OAGB mean operative time and post-surgery hospital stay were significantly shorter
48 compared to RYGB (109 ± 23 vs 180 ± 36 min and 5.4 ± 1.0 vs 8.7 ± 4.6 days P<0.001 for
49 both parameters). One year post-surgery, significantly greater decreases were observed in
50 OAGB versus RYGB considering weight (-47 vs -36 kg P<0.001), body mass index (-17.3 vs
51 -12.6 kg/m² P<0.001), excess weight loss (85.8 vs 65.2% P<0.001), total weight loss (37.7 vs
52 28.9% P=0.006), fat mass (-35 vs -27 kg P=0.002), lean mass (-7 vs -5 kg P=0.03), diabetes
53 remission (92 vs 60% P=0.04), glycated hemoglobin (5.4 vs 6.3% P<0.001) and a significantly
54 greater increase in high density lipoprotein-cholesterol (+0.25 vs +0.16 mmol/L P=0.04). In
55 both groups, nutritional disorders, increasing over time, were common and showed no
difference in evolution. Rates of early or late surgical complications were similar but more
56 severe in the RYGB group.

58 **Conclusions:** OAGB was simpler, safer and showed greater improvements in weight loss or
59 glucose and lipid metabolic parameters compared to RYGB at 1-year follow-up.

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61 **Abstract text word count:** 270
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63 **Keywords:** Bariatric surgery; Nutrition; Nutritional disorders; Obesity; One anastomosis

64 gastric bypass; Roux-en-Y gastric bypass; Surgical complications.

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66 **Highlights**

67 OAGB is superior to RYGB in terms of weight loss and diabetes remission

68 OAGB is simpler and safer than RYGB with less severe post-surgical complications

69 Pre-surgery nutritional disorders are common and increase over time in both surgeries

70 OAGB nutritional and safety outcomes need to be assessed in larger and longer studies
## INTRODUCTION

Obesity represents a worldwide public health problem. The World Health Organization (WHO) estimated its prevalence in 2016 at around 650 million people in the world (1), a number which continues to increase in both developed and developing countries. Many studies have shown a strong association between obesity and morbi-mortality (2,3) which can be explained by obesity-related comorbidities including metabolic (diabetes, dyslipidemia), respiratory (obstructive sleep apnea syndrome), mechanical and cardiovascular (arterial hypertension, atherosclerosis with coronary heart disease or stroke) disorders which are the dominant causes in obesity (4). These comorbidities lead to a marked reduction in life expectancy when compared to normal-weight subjects.

The effectiveness of bariatric surgery in resolving obesity-related comorbidities and decreasing mortality in addition to improving quality of life (5), when compared to conventional weight-reducing treatments, has led to an exponential increase in these surgical procedures in a few decades (6).

Numerous surgical procedures have been developed including adjustable gastric banding, sleeve-gastrectomy, biliopancreatic diversion with duodenal switch, and gastric bypass. The Roux-en-Y gastric bypass (RYGB) is generally considered to be the gold standard (7,8) but a modified gastric bypass, termed one anastomosis gastric bypass (OAGB), has emerged more recently (9). This new technique considered as a simpler procedure than RYGB began to increase quickly in frequency from 0.6 to 4.8% of the total bariatric procedures between 2011 and 2016 (10). However OAGB procedure remains questioned and is still not fully accepted worldwide, with areas of non-consensus regarding the technique (11). There is still no consensus In 2022, the American Society for Metabolic and Bariatric Surgery discussed whether to endorse the OAGB procedure despite its superiority on weight loss and metabolic outcomes compared with RYGB having not been established and in the light of the persisting controversy of a potential degenerative risk of gastric or oesophageal mucosa in the long term. OAGB has been approved but is still
a controversial procedure that is currently being debated. Further trials of high scientific value are naturally needed to confirm

these findings and provide solid data regarding indications and technical aspects of the OAGB (12–16).

Ghiassi (12)

Robert (16)

Ramos (15)

De Luca (13)

Haddad (14)

Sheldrick (17)

Pournaras (18)

Wiggins (19)

Cohen (20)

Rassy (21)

While a consensus statement by the international federation of obesity task force recognized

OAGB as an acceptable surgical option with long-term multidisciplinary follow-up (9), in

France the technique was banned in 2019 by the High Authority of Health outside a randomized

clinical trial. The most important concerns were the lack of data regarding the efficacy and

safety outcomes of this procedure (22).

In the present real life study, we compared the efficacy and safety outcomes of OAGB versus

RYGP over the short-term (12 months post-surgery).

## SUBJECTS AND METHODS

### Subjects

We performed a retrospective analysis of a prospectively maintained database of consecutive

patients who underwent bariatric surgery between 2007 to 2017. All participants were examined

and followed by a multidisciplinary and integrated medical team in our Nutrition Department,

consisting of an endocrinologist, a bariatric surgeon, a psychiatrist, and a dietician for at least

6 months before surgery. All subjects met the indication criteria for bariatric surgery (23). The

choice of the surgical procedure was not randomized but made by the patient and the
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multidisciplinary team, after a full explanation of the risks and possible benefits of each

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procedure. Bariatric surgery was performed by a single surgeon in the General and Endocrine

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Surgery Department. The single surgeon was used to avoid different levels of experience and
learning curves between surgeons. The surgical technique employed was firstly RYBP from

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2007 to 2013 and then OAGB from 2013 to 2017. Fifty patients who underwent RYGB and 45

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patients OAGB were consecutively selected. Only patients who completed a follow-up of 12

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months were included. This study was conducted in accordance with the Declaration of
Helsinki, approved by the Research Ethics Board and all subjects gave written informed

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consent.

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Study design

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The subjects were examined and followed by the multidisciplinary team before surgery and at
least at 1, 3, 6, 9 and 12 months post-surgery, with laboratory tests and body composition
analysis performed 1 month before (M0) and 12 months (M12) after surgery. Systematic
supplementation with vitamins and minerals was uniformly prescribed to all patients after
surgery. During the follow-up at 1, 3, 6, 9 and 12 months, treatments such as antidiabetic agents,
antihypertensive drugs or lipid-lowering therapies, as well as vitamin and mineral
supplementation were adjusted by the physician, according to routine consultation and
depending on the results of blood tests performed in the fasting state.

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The parameters assessed at M0 and M12 were the following:

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Demographic and anthropometric parameters: age, gender, tobacco use, history of bariatric
surgery, weight, height, and body mass index (BMI). Excess weight loss (EWL) was defined
as the operative weight minus the 12 months follow-up weight, divided by the excess weight,
multiplied by 100; total weight loss (TWL) was defined as operative weight minus the 12
months follow-up weight, divided by the operative weight, multiplied by 100. Body

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composition (fat and lean mass) was measured using the dual-energy X-ray absorptiometry method (Lunar iDXA, GE Healthcare, Chalfont, St Giles, UK).

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**Metabolic outcomes:** carbohydrate metabolism evaluation included plasma glucose, insulin, C-peptide, and glycated hemoglobin (HbA1C) only in diabetic patients, Homeostasis Model Assessment-Insulin Resistance Index calculation (HOMA-IR index): [fasting insulin (mUI/L) x fasting glucose (mmol/L)/22.5)] was calculated only in non-diabetic patients and lipid metabolism evaluation consisted of plasma total cholesterol, low density lipoprotein-cholesterol (LDL-c), high density lipoprotein-cholesterol (HDL-c) and triglycerides measurements.

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**Biochemical nutritional parameters:** hemoglobin, vitamin assays (vitamin A, E, D, B1, B9, B12), trace-elements (zinc, selenium, globular magnesium and ferritin). Malnutrition was characterized by albumin level < 35 g/L and/or transthyretin level < 0.25 g/L; anemia defined by a hemoglobin level < 120 g/L for women and < 130 g/L for men; vitamin deficiency: vitamin A concentration < 0.41 mg/L, vitamin E concentration < 8 mg/L, vitamin D concentration < 50 nmol/L, vitamin B1 concentration < 67 nmol/mL, vitamin B9 concentration < 8.8 nmol/L, vitamin B12 concentration < 145 pmol/L; trace-element deficiency : ferritin < 22 ng/mL, globular magnesium < 1.6 mmol/L, zinc < 60 mg/100 mL, selenium < 60 mg/L.

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**Obesity-related comorbidities:** type 2 diabetes (defined by a preexisting treatment for diabetes or a fasting plasma glucose ≥ 1.26 g/L and/or post-prandial plasma glucose ≥ 2 g/L); dyslipidemia (defined by a preexisting lipid-lowering therapy or a fasting plasma triglycerides > 1.50 g/L and/or LDL-c > 1.30 g/L and/or HDL-c < 0.40 g/L); arterial hypertension (defined by a preexisting antihypertensive treatment); OSAS (defined by apnea-hypopnea index > 15/hours or the use of a continuous positive airway pressure therapy). At 12 months after gastric bypass, complete remission of type 2 diabetes was defined, according to American Diabetes Association (ADA) recommendations (24), by a fasting plasma glucose less than 1 g/L and/or

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a glycated hemoglobin less than 5.7% in the absence of hypoglycemic treatment; remission of
arterial hypertension was defined by a normal blood pressure (< 140/90 mmHg) without
antihypertensive treatment; remission of OSAS was defined by the cessation of the continuous
positive airway pressure; remission of dyslipidemia was defined by fasting plasma triglycerides
$\leq 1,5$ g/L and LDL-c $\leq 1.30$ g/L and HDL-c $\leq 0.40$ g/L in the absence of a lipid-lowering
therapy.

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## 180 Surgical procedures

All gastric bypass procedures were performed laparoscopically by the same surgeon and were
standardized. RYGB consisted of a small gastric pouch (30 to 50 ml), a 120 cm alimentary limb
for patients with BMI < 50 kg/m² and 150 cm for patients with BMI $\geq 50$ kg/m² and a 50 cm
biliopancreatic limb. OAGB consisted of a long gastric tube beginning at the landmark of the
incisura angularis and calibrated with a 34 French bougie. A single gastrojejunal anastomosis
was done using a linear stapler with a biliopancreatic limb of 200 cm. To compare the 2
procedures, we assessed the operative time (beginning at the incision and ending at suturing)
and the post-operative hospital stay. We also collected all post-operative complications that
occurred within the first year after surgery. Complications were divided into early
complications (within the first 30 days after surgery) and late complications (from 30 days to 1
year after surgery). All surgical complications were classified according to the standardized
Clavien-Dindo classification (15,16).

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## 194 Statistical analysis

Statistical analysis was performed using IBM SPSS Statistics 20.0 (IBM Inc., New York, USA)
and carried out by a statistician. Quantitative variables were summarized using mean plus or
minus standard deviation. Qualitative variables were summarized by counts and percentage
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of cases. Student *t*-test was used to compare OAGB and RYGB quantitative variables collected pre-surgery (M0) and post-surgery (M12). Comparison of qualitative variables was performed using Chi-square test or Fisher's exact test. Comparison of ordinal variables (Clavien-Dindo) was performed using Mann-Whitney test. Pairwise comparisons of groups was done using paired t-tests to compare the evolution of parameters (ΔM12-M0). Values of p < 0.05 were considered significant.

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# RESULTS

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## Pre-surgery baseline characteristics

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The baseline characteristics of the patients are reported in Tables 1, 2 and 3. The majority of patients were female (74%) and the OAGB group was younger than the RYGB group (p = 0.03). We found no significant differences in the other parameters that were assessed but a trend towards a higher LDL-c and a lower HbA1C in the OAGB compared to the RYBG group was observed.

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At baseline, no difference was observed in nutritional parameters between the 2 groups however the number of deficiencies/patient was higher in the OAGB group vs RYGB (2.3 vs 1.1 deficiencies per patient, p < 0.0001) (Table 3).

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## Effects of surgery:

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### Anthropometric parameters

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When pre-surgery to post-surgery (1 month before vs 12 months after surgery: ΔM12-M0) was compared, we found a significant decrease in weight, BMI, fat mass and lean mass in both groups (p < 0.001 for all parameters) but a greater significant reduction of all these parameters as well as a higher significant increase in EWL and TWL was found in the OAGB group
compared to the RYGB group (p = 0.006 for TWL, p = 0.002 for fat mass, p = 0.03 for lean mass and p < 0.001 for all other parameters) (Table 2).

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## Metabolic outcomes

In ΔM12-M0 analyses of plasma lipid and carbohydrate metabolic parameters, all parameters were significantly improved in both groups (p = 0.014 for total cholesterol in the RYGB group, p = 0.001 or < 0.001 for all other parameters). A significantly greater increase in HDL-c in the OAGB group compared to the RYGB group was observed (p = 0.04) (Table 2).

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## Nutritional outcomes

After surgery (M12), more deficiencies/patient and more vitamin A and zinc deficiencies in the OAGB group compared to the RYGB group were still observed (p < 0.002, p = 0.002 and p = 0.002 respectively). In ΔM12-M0 analyses, we found no difference between the 2 groups (Table 3).

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## Obesity-related comorbidities

After surgery (M12), we found a significant decrease in all obesity-related comorbidities in both groups, with the exception of hypertension (Table 4).

For type 2 diabetes, there was a significant decrease in the prevalence of type 2 diabetes in the OAGB group (p < 0.001) and in the RYGB group (p = 0.007) but the prevalence of type 2 diabetes was significantly lower (p = 0.02), and both the remission of type 2 diabetes and the decrease in HbA1C were significantly greater in the OAGB group compared to RYGB group (p = 0.04 and p < 0.001 respectively).

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245 For dyslipidemia, there was a significant decrease in prevalence in both the OAGB group (p < 0.001) and the RYGB group (p < 0.001) after surgery, with no significant difference in remission between the OAGB and RYGB groups (p = 0.26).
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248 Similarly, for OSAS, there was a significant decrease in the prevalence in both the OAGB group (p = 0.003) and the RYGB group (p < 0.001) after surgery, with no significant difference in remission observed between groups (p = 0.16).
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251 Lastly, no change was observed in the prevalence of hypertension after gastric bypass in either group.
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254 Surgical outcomes

255 The mean operative time and the post-operative hospital stay were significantly shorter in the OAGB group compared to the RYGB group (p < 0.001 for both). We found no difference in either the number of patients with complications between the OAGB (n = 8, 18%) and RYGB (n = 8, 16%) groups, or in the number of early (2 vs 5) or late (7 vs 3) post-operative complications between the OAGB and RYGB groups. According to the Clavien-Dindo classification, complications were more severe in the RYGB group than in the OAGB group (p = 0.005) (Table 5).
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263 DISCUSSION

264 In the present real life short-term (1 year) study, we found that OAGB was superior to RYGB in terms of anthropometric outcomes, including the following parameters: decrease in weight, BMI, fat mass and lean mass, and increase in EWL and TWL. Metabolic outcomes were also superior: increased HDL-c, a decrease in HbA1C; and also obesity-related comorbidities, specifically a higher remission rate of type 2 diabetes. These improvements were not
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accompanied by an increased risk of nutritional deficiencies, nor by an increase in early or late
surgical complications.

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In terms of anthropometric outcomes, our results were in agreement with the first randomized
study that compared OAGB and RYGB (27), and with 2 recent meta-analyses showing a greater
significant increase in EWL at 1 year for OAGB (18,19). In the longer term, the results have not
been homogeneous between studies, with superiority of OAGB compared to RYGB, in terms
of EWL, found at 2 and 5 years post-surgery in one meta-analysis (29), but no difference
observed at 2 years in two randomized studies (17, 20). The mean EWL in our study (86% in
OAGB and 65% in RYGB) is consistent with the mean EWL at 1 year for the 4 studies included
in the most recent meta-analysis (84% in OAGB and 72% in RYGB) (28). The length of the
limbs (200 cm for the biliopancreatic limb in the OAGB group and 120 to 150 cm for the
alimentary limb depending on the BMI and 50 cm for the biliopancreatic limb in the RYGB
group in our study) could explain the different results reported in these studies. We described
here for the first time higher fat mass loss, but also lean mass loss, for OAGB treatment
compared to RYGB.

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In terms of metabolic outcomes, we found a drastic improvement in glucose homeostasis in
both OAGB and RYGB, but superiority of OAGB in terms of decrease in HbA1C. This has
been confirmed in one study at 2 years (30). We also confirmed the improvement in insulin
sensitivity (decrease of HOMA-IR), which has already been reported after RYGB (21, 22) and
OAGB (23, 24), with no difference found between the 2 procedures. Similarly, lipid parameters
were clearly improved in both groups, as was reported in another study at 2 years, but with a
higher increase in HDL-c in the OAGB group in our study. Hypertriglyceridemia is a major
factor contributing to HDL catabolism but in our study we found no difference in the decrease
of fasting plasma TG between groups (35). However, the higher incidence of diarrhea and more
frequently reported steatorrhea in the OAGB group compared to RYGP group, suggests a
greater malabsorptive effect of the OAGB procedure (20, 26). This effect could explain a decrease in postprandial lipemia in OAGB vs RYGB, leading to a greater increase of HDL-c in OAGB (37). Furthermore, glycemic imbalance has a deleterious effect on HDL metabolism, and the greater improvement in blood glucose control seen in OAGB could play a role in the difference in post-surgical HDL-c levels. Lastly, a significant negative correlation has already been reported between HDL catabolism and plasma adiponectin, independent of insulin resistance and plasma lipids (35). We cannot exclude that the greater decrease in fat mass in the OAGB group could lead to a larger increase in plasma adiponectin in this group, with a decrease in HDL catabolism and a greater increase in HDL-c. Unfortunately, plasma adiponectin could not be measured in our study.

As expected, in both groups, all comorbidities (T2D, dyslipidemia and OSAS) with the exception of arterial hypertension, were improved after surgery, but we found that OAGB was superior in decreasing the prevalence and increasing remission of type 2 diabetes post-surgery compared to RYGB. Our results are broadly similar to those of one recent meta-analysis (except for OSAS which was not reported in this study) (29). In a randomized study, despite more patients achieving remission of type 2 diabetes in the OAGB group than the RYGB group, the difference was not significant. In the present study, the older subject age, the trend towards a longer duration of diabetes and more patients being on insulin treatment (12 vs 1) in the RYGB vs OAGB group are negative predictive factors of diabetes remission (38) that may explain the difference between the 2 groups.

In terms of nutritional outcomes, nutritional disorders in both groups were already observed in pre-surgery. The OAGB group had more deficiencies/patient than the RYGB group (2.3 vs 1.1) but no difference was found between groups if we considered the nutritional parameters individually. The most common abnormalities for the whole cohort were malnutrition and vitamin D deficiency. These results are in accordance with several previous studies, which have
shown that patients with obesity present nutritional disorders before surgery (29, 30). In post-surgery, the most common abnormalities for the whole cohort were malnutrition and selenium deficiency. The OAGB group maintained more deficiencies/patient than the RYGB group (2.9 vs 1.9) but the evolution between pre- and post-surgery for this parameter, as well as all the other nutritional parameters, were not different between the OAGB and RYGB groups. The nutritional parameters that were assessed were not strictly the same between studies, but our results are in agreement with studies that have compared OAGB and RYGB. Zarshenas et al. have shown that nutritional disorders were common in both cohorts and increased over time (2 years post-surgery), but with no difference between the 2 groups (36). Robert et al. reported no difference between the 2 groups at 2 years after surgery, except for a significant difference in the mean decrease in hemoglobin in the OAGB group but no difference found between the groups for the incidence of anemia or iron deficiency (30). To our knowledge, our study was the first to assess the evolution of several micronutrients such as zinc, selenium and magnesium after the 2 procedures. We confirmed, in our study, that despite a rigorous follow-up (consultations at 1, 3, 6, 9 and 12 months after surgery) by an experienced multidisciplinary medical team, including regular adaptation of dietary advice and vitamin and mineral supplementations according to food intake and blood tests, the risk of nutritional disorders remains a concern in bariatric surgery. This observation led the American Society for Metabolic and Bariatric Surgery (ASMBS) to publish guidelines to improve the general nutritional knowledge necessary for the care of pre- and post-operative patients (40).

In terms of surgical outcomes, we confirmed the greater simplicity of OAGB vs RYGB, with a shorter operative time (17, 19) and shorter post-operative hospital stay in the OAGB group (27).

We found that the OAGB procedure was as safe as RYGB, with an even greater severity of complications observed for RYGB. It is worth noting that we had no deaths in our study. The comparison of complications between the 2 surgical techniques remains a matter of debate.
Differences in results between studies could be explained by several factors including: the level of experience of the surgeon, the number of surgeons with different learning curves, the different surgical techniques used, and in particular the length of the limbs, the duration of follow-up, and the complications that were considered. Lee et al. found more early post-operative complications in the RYGB group (n=8, 20%) compared to the OAGB group (n=3, 7.5%) with 2 (2 anastomotic leaks) vs 0 major and 6 vs 3 minor complications in the RYGB vs OAGB groups (27). Level et al. reported, at 5 years follow-up, only one operative complication in the OAGB group and no major post-operative complications or mortality in either group (34). In the study by Robert et al., at 2 years of follow-up, the serious adverse events associated with surgery were significantly higher in the OAGB group vs RYGB group (42 vs 24, p = 0.042). However, in this latter study, nutritional complications were included in the group of complications that showed a significant difference between the RYGB vs OAGB groups (0 vs 9) (30). In the meta-analysis by Magouliotis et al., the incidence of anastomotic leak, marginal ulcer, dumping, and revision or mortality were all comparable between the OAGB and RYGB groups (29).

Our study also has several limitations: this was a non-randomized study with a restricted number of patients included and with a short follow-up period. Our study was not designed to assess the risk of biliary reflux that has been described with OAGB and the potential risk of gastric and oesophageal cancer. Therefore, prospective randomized studies including more patients and with long-term follow-up are needed.

## Conclusions

The present study demonstrated, at 1-year follow-up, that OAGB and RYGB were both effective treatments for morbid obesity but that OAGB was superior in terms of weight loss, improvement of glucose metabolism, type 2 diabetes remission and HDL-c increase. OAGB
369 was also shown to be simpler and safer than RYGB, with the same number of early and late
370 complications, and with more severe complications in the RYGB group. Nutritional disorders
371 were frequent in pre-surgery for both groups and persisted in post-surgery despite systematic
372 supplementation and rigorous follow-up in a specialized department. Thus, OAGB could
373 represent an alternative to RYGB but longer and larger studies are now needed to assess the
374 longer-term side effects of OAGB.

375

376 **Declarations**

377 **Ethics approval:** This study was conducted in accordance with the Declaration of Helsinki,
378 approved by the Research Ethics Board and all subjects gave written informed consent.

379 **Funding:** none

380 **Author contributions:** LP contributed to write the report, to extract and analyze data and to
381 interprete results. FM contributed to subjects medical follow-up and to data extraction. BB was
382 responsible for surgical interventions, contributed to data extraction and to subjects medical
383 follow-up, JM was responsible for statistical analyses. AB contributed to the design of the
384 protocol to subjects medical follow-up and data extraction. JPN contributed to data extraction
385 and provided feedback on the report. JD contributed to data extraction. ND contributed to
386 subjects medical follow-up. RG contributed to subjects medical follow-up. SB contributed to
387 subjects medical follow-up. MM and RV conducted the design of the protocol, the data
388 extraction and analyze, the results interpretation and the report writing.

389 **Conflict of interest:** The authors declare that they have no conflict of interest.

390 **Data availability statement:** The datasets generated during and/or analysed during the current
391 study are available from the corresponding author on reasonable request.
392 REFERENCES

393 1. World Health Organization: Overweight and Obesity in 2016. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight. Disponible sur:
394 395 https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight

396 2. Calle EE, Thun MJ, Petrelli JM, Rodriguez C, Heath CW. Body-mass index and mortality in a prospective cohort of U.S. adults. N Engl J Med. 7 oct 1999;341(15):1097-105.
397

398 3. Adams KF, Schatzkin A, Harris TB, Kipnis V, Mouw T, Ballard-Barbash R, et al.
399 Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years
400 old. N Engl J Med. 24 août 2006;355(8):763-78.

401 4. Prospective Studies Collaboration, Whitlock G, Lewington S, Sherliker P, Clarke R, 402 Emberson J, et al. Body-mass index and cause-specific mortality in 900 000 adults: 403 collaborative analyses of 57 prospective studies. Lancet Lond Engl. 28 mars 404 2009;373(9669):1083-96.

405 5. Sjöström L, Lindroos AK, Peltonen M, Torgerson J, Bouchard C, Carlsson B, et al.
406 Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl
407 J Med. 23 déc 2004;351(26):2683-93.

408 6. Santry HP, Gillen DL, Lauderdale DS. Trends in bariatric surgical procedures from 1997 409 to 2003. JAMA. 19 oct 2005;294(15):1909-17.

410 7. Li J, Lai D, Wu D. Laparoscopic Roux-en-Y Gastric Bypass Versus Laparoscopic Sleeve 411 Gastrectomy to Treat Morbid Obesity-Related Comorbidities: a Systematic Review and 412 Meta-analysis. Obes Surg. févr 2016;26(2):429-42.

413 8. Yan Y, Sha Y, Yao G, Wang S, Kong F, Liu H, et al. Roux-en-Y Gastric Bypass Versus 414 Medical Treatment for Type 2 Diabetes Mellitus in Obese Patients: A Systematic Review 415 and Meta-Analysis of Randomized Controlled Trials. Medicine (Baltimore). avr 416 2016;95(17):e3462.

417 9. De Luca M, Tie T, Ooi G, Higa K, Himpens J, Carbajo MA, et al. Mini Gastric Bypass- 418 One Anastomosis Gastric Bypass (MGB-OAGB)-IFSO Position Statement. Obes Surg. 419 mai 2018;28(5):1188-206.

420 10. Angrisani L, Santonicola A, Iovino P, Vitiello A, Higa K, Himpens J, et al. IFSO 421 Worldwide Survey 2016: Primary, Endoluminal, and Revisional Procedures. Obes Surg. 422 déc 2018;28(12):3783-94.

423 11. Kermansaravi M, DavarpanahJazi AH, ShahabiShahmiri S, Carbajo M, Vitiello A, 424 Parmar CD, et al. Areas of Non-Consensus Around One Anastomosis/Mini Gastric 425 Bypass (OAGB/MGB): A Narrative Review. Obes Surg. juin 2021;31(6):2453-63.

426 12. Ghiassi S, Nimeri A, Aleassa EM, Grover BT, Eisenberg D, Carter J, et al. American 427 Society for Metabolic and Bariatric Surgery position statement on one-anastomosis 428 gastric bypass. Surg Obes Relat Dis Off J Am Soc Bariatr Surg. avr 2024;20(4):319-35.
429

430

431

13. De Luca M, Piatto G, Merola G, Himpens J, Chevallier JM, Carbajo MA, et al. IFSO
Update Position Statement on One Anastomosis Gastric Bypass (OAGB). Obes Surg. juill
2021;31(7):3251-78.

432

433

434

14. Haddad A, Bashir A, Fobi M, Higa K, Herrera MF, Torres AJ, et al. The IFSO Worldwide
One Anastomosis Gastric Bypass Survey: Techniques and Outcomes? Obes Surg. avr
2021;31(4):1411-21.

435

436

437

438

15. Ramos AC, Chevallier JM, Mahawar K, Brown W, Kow L, White KP, et al. IFSO
(International Federation for Surgery of Obesity and Metabolic Disorders) Consensus
Conference Statement on One-Anastomosis Gastric Bypass (OAGB-MGB): Results of a
Modified Delphi Study. Obes Surg. mai 2020;30(5):1625-34.

439

440

441

442

16. Robert M, Poghosyan T, Maucort-Boulch D, Filippello A, Caiazzo R, Sterkers A, et al.
Efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass at
5 years (YOMEGA): a prospective, open-label, non-inferiority, randomised extension
study. Lancet Diabetes Endocrinol. avr 2024;12(4):267-76.

443

444

17. Sheldrick RC. Randomized Trials vs Real-world Evidence: How Can Both Inform
Decision-making? JAMA. 25 avr 2023;329(16):1352-3.

445

446

447

18. Pournaras DJ, Aasheim ET, Søvik TT, Andrews R, Mahon D, Welbourn R, et al. Effect of
the definition of type II diabetes remission in the evaluation of bariatric surgery for
metabolic disorders. Br J Surg. janv 2012;99(1):100-3.

448

449

450

451

19. Wiggins T, Jamel S, Hakky S, Ahmed A, Markar SR, Hanna GB. Assurance of surgical
quality within multicenter randomized controlled trials for bariatric and metabolic
surgery: a systematic review. Surg Obes Relat Dis Off J Am Soc Bariatr Surg. janv
2022;18(1):124-32.

452

453

454

20. Cohen R, Le Roux CW, Junqueira S, Ribeiro RA, Luque A. Roux-En-Y Gastric Bypass in
Type 2 Diabetes Patients with Mild Obesity: a Systematic Review and Meta-analysis.
Obes Surg. oct 2017;27(10):2733-9.

455

456

457

21. Rassy N, Rives-Lange C, Carette C, Barsamian C, Moszkowicz D, Thereaux J, et al. Spin
occurs in bariatric surgery randomized controlled trials with a statistically nonsignificant
primary outcome: A systematic review. J Clin Epidemiol. nov 2021;139:87-95.

458

459

460

461

22. Haute Autorité de Santé - Traitement chirurgical de l'obésité sévère et massive par court-circuit (bypass) gastrojéjunal avec anse en oméga. sept 2019; Disponible sur: https://www.has-sante.fr/upload/docs/application/pdf/2019-09/rapport_bypass_gastrique_en_omega_vd.pdf

462

463

464

23. Haute Autorité Santé guidelines. Obésité: prise en charge chirurgicale chez l'adulte
[Internet]. Haute Autorité Santé guidelines; 2009. Disponible sur: http://www.has-sante.fr/

465

466

24. Buse JB, Caprio S, Cefalu WT, Ceriello A, Del Prato S, Inzucchi SE, et al. How do we
define cure of diabetes? Diabetes Care. nov 2009;32(11):2133-5.

467

468

25. Clavien PA, Sanabria JR, Strasberg SM. Proposed classification of complications of
surgery with examples of utility in cholecystectomy. Surgery. mai 1992;111(5):518-26.
469

470

471

26. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg. août 2004;240(2):205-13.

472

473

474

27. Lee WJ, Yu PJ, Wang W, Chen TC, Wei PL, Huang MT. Laparoscopic Roux-en-Y versus mini-gastric bypass for the treatment of morbid obesity: a prospective randomized controlled clinical trial. Ann Surg. juill 2005;242(1):20-8.

475

476

477

28. Uhe I, Douissard J, Podetta M, Chevallay M, Toso C, Jung MK, et al. Roux-en-Y gastric bypass, sleeve gastrectomy, or one-anastomosis gastric bypass? A systematic review and meta-analysis of randomized-controlled trials. Obesity. mars 2022;30(3):614-27.

478

479

480

29. Magouliotis DE, Tasiopoulou VS, Tzovaras G. One Anastomosis Gastric Bypass Versus Roux-en-Y Gastric Bypass for Morbid Obesity: an Updated Meta-Analysis. Obes Surg. sept 2019;29(9):2721-30.

481

482

483

484

30. Robert M, Espalieu P, Pelascini E, Caiazzo R, Sterkers A, Khamphommala L, et al. Efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass for obesity (YOMEGA): a multicentre, randomised, open-label, non-inferiority trial. Lancet Lond Engl. 6 mars 2019;

485

486

31. Bojsen-Møller KN. Mechanisms of improved glycaemic control after Roux-en-Y gastric bypass. Dan Med J. avr 2015;62(4):B5057.

487

488

489

32. Faria G, Preto J, da Costa EL, Guimarães JT, Calhau C, Taveira-Gomes A. Acute improvement in insulin resistance after laparoscopic Roux-en-Y gastric bypass: is 3 days enough to correct insulin metabolism? Obes Surg. janv 2013;23(1):103-10.

490

491

492

493

494

33. Kaska Ł, Proczko M, Wiśniewski P, Stankiewicz M, Gill D, Śledziński Z. A prospective evaluation of the influence of three bariatric procedures on insulin resistance improvement. Should the extent of undiluted bile transit be considered a key postoperative factor altering glucose metabolism? Wideochirurgia Inne Tech Maloinwazyjne Videosurgery Miniinvasive Tech. juill 2015;10(2):213-28.

495

496

497

34. Level L, Rojas A, Piñango S, Avariano Y. One anastomosis gastric bypass vs. Roux-en-Y gastric bypass: a 5-year follow-up prospective randomized trial. Langenbecks Arch Surg. févr 2021;406(1):171-9.

498

499

35. Vergès B. Pathophysiology of diabetic dyslipidaemia: where are we? Diabetologia. mai 2015;58(5):886-99.

500

501

502

503

36. Zarshenas N, Tapsell LC, Batterham M, Neale EP, Talbot ML. Changes in Anthropometric Measures, Nutritional Indices and Gastrointestinal Symptoms Following One Anastomosis Gastric Bypass (OAGB) Compared with Roux-en-Y Gastric Bypass (RYGB). Obes Surg. juin 2021;31(6):2619-31.

504

505

506

37. Desmarchelier C, Borel P, Lairon D, Maraninchi M, Valéro R. Effect of Nutrient and Micronutrient Intake on Chylomicron Production and Postprandial Lipemia. Nutrients. 8 juin 2019;11(6):E1299.

507

508

38. Park JY, Kim YJ. Prediction of Diabetes Remission in Morbidly Obese Patients After Roux-en-Y Gastric Bypass. Obes Surg. avr 2016;26(4):749-56.
509
510

39. Toh SY, Zarshenas N, Jorgensen J. Prevalence of nutrient deficiencies in bariatric patients. Nutr Burbank Los Angel Cty Calif. déc 2009;25(11-12):1150-6.

511
512
513
514

40. Parrott J, Frank L, Rabena R, Craggs-Dino L, Isom KA, Greiman L. American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients. Surg Obes Relat Dis Off J Am Soc Bariatr Surg. mai 2017;13(5):727-41.

515