This study first presents the organizational path and the health interventions included in the care episode for outpatient bariatric surgery, as compared to the health interventions usually performed in the care episode for bariatric surgery (including a conventional hospitalization with at least one-night inpatient). Then, the study aims to estimate and to compare the costs of bariatric surgery inpatient care episode to the costs of outpatient care episode, and also to evaluate the postoperative medical consequences.

This study first presents the organizational path and the health interventions included in the care episode for outpatient bariatric surgery, as compared to the health interventions usually performed in the care episode for bariatric surgery (including a conventional hospitalization with at least one-night inpatient).

This single-center, matched case-control study will be conducted in the Endocrine and Digestive Surgery Unit, Center of Excellence in Bariatric Surgery, of the University Hospital of Strasbourg. All the patients scheduled for bariatric procedures (Roux-en-Y gastric bypass and Sleeve Gastrectomy) and eligible for outpatient ambulatory procedures, will be checked for the inclusion criteria and will be asked if they accepted the outpatient bariatric procedure. If they accept, they will be included in the group A ("Outpatients"). At the end of the inclusion period, the patients in group A will be paired to patients who were operated in the same period, who had a conventional hospitalization and who will be matched based on the type of intervention, the age and the ASA status. These patients will form the group B ("Inpatients").

The integrated care pathway of the outpatients was formalized in order to secure this care pathway. It includes: patient education, enhanced rehabilitation program, first-position surgical planning, follow-up by home nurse twice-a-day, standardized communication to surgeons, and management of possible complications. All the health care interventions (anticipated or not) will be recorded for both groups.

The study aims to estimate and to compare the costs of bariatric surgery inpatient care episode to the costs of outpatient care episode, and also to evaluate the postoperative medical consequences. A cost-minimization analysis will be performed from the perspective of the healthcare provider. The direct costs of care production will be considered and estimated by a micro-costing methodology. The time horizon is set from the pre-operative outpatient appointment with the bariatric surgeon to the one-month post-operative appointment.

Inclusion Criteria:

• Patient between the age of 18 and 60
• Patient with a BMI of more than 35 with comorbidities or BMI of more than 40
• Speaking and understanding French
• Access to a phone
• Access to a suitable healthcare facility near his residence
• Appropriate post-operative residence
• Moderate and/or controlled comorbidities
• Patient able to understand research objectives and risks and to give informed consent
• Patient not living alone
• affiliated to the French health insurance system

Exclusion Criteria:

• patient unable to provide informed consent
• Previous bariatric surgery
• Previous laparotomy
• BMI of more than 50
• Insulin-dependent diabetes
• Uncorrected preoperative anaemia
• Anticoagulation that cannot be interrupted
• Ischemic heart disease
• Untreated obstructive sleep apnea syndrome (OSA)
• dialysis
• Liver cirrhosis
• Subject under guardianship, curatorship, safeguarding/protection of justice
• Pregnancy
• Breastfeeding