Franny Jongbloed

158 CHAPTER 6 study is performed in accordance with the local METC guidelines. The trial is registered as part of the PROTECT trial in the Dutch trial registry database using trial code 3663 (www.trialregister.nl) . This study was performed in accordance with the CONSORT 2010 statement, according to the Declaration of Helsinki 38 . Healthy living kidney donors and healthy volunteers that gave written informed consent served as age-matched healthy controls (HC) (n=10) and the study was approved by the Medical Ethical Committee of the Erasmus MC (Biobank of the METC, METC number 2012-022). Study population Patients with obesity and morbid obesity scheduled to undergo bariatric surgery whom visited the outpatient clinic at the Maasstad Hospital between March 2014 and August 2015 were invited to participate in the study. All participating patients gave written informed consent before inclusion. A patient flowchart showing all inclusions and exclusions is depicted in Figure S1. To be eligible for bariatric surgery, patients had to have a body mass index (BMI, kg/m2 ≥35 with or without he presence of the metabolic syndrome (MetS). MetS was defined in accordance to the National Cholesterol Education Program ATPIII Guidelines, as fulfilling 3 out of 5 criteria 39 . Exclusion criteria were a BMI<35, other comorbidities than MetS, patients without basic understanding of the Dutch or English language, or patients undergoing another form of bariatric surgery than a laparoscopic gastric bypass procedure (LGBP). Bariatric surgery The LGBP was used in all patients. In short, the jejenum is divided at 50 cm from the ligament of Treitz into a biliopancreatic limb and a 150-cm alimentary Roux-limb. The proximal segment of the stomach is made into a small pouch with stapling devices. A side- to-side anastomosis is created between the pouch and the Roux-limb. The biliopancreatic limb is connected to the Roux limb, 150 cm distally. Blood collection After providing written informed consent, a venous blood sample was obtained prior to surgery.The duration until scheduled surgery was between several days and fivemonths after first blood sample. At time points prior to bariatric surgery, venous samples of 108 patients were collected for analysis. A selection of patients was asked to donate another venous blood sample at time points three (n=48), six (n=10) and 12 (n=11) months after surgery (Figure S1). The selection was made since not all patients showed up in the outpatient clinic during their scheduled follow-up clinics, or patients decided to be followed-up elsewhere