Cardiovascular Outcomes Improved by Bariatric Surgery Independent of Baseline BMI

Setting and participants. The Swedish Obese Subjects (SOS) trial is one of the largest and longest-running prospective trials of bariatric surgery in the world. Participants were enrolled between 1987 and 2001 from 480 Swedish primary health care centers. Individuals were eligible to participate if they were between 37 and 60 years of age and obese (minimum BMI of 34 for men and 38 for women) but had not had previous bariatric or gastric/duodenal ulcer surgery, recent gastric ulcer, ongoing or recent (within 5 years) malignancy, recent (within 6 months) myocardial infarction (MI), drug or alcohol abuse, or other behavioral and psychological problems. Of 5335 eligible patients, 2010 elected to undergo surgery. They were matched with 2037 control participants based on 18 baseline variables. Intervention patients underwent 1 of 3 surgeries: 376 (18.7%) had gastric banding, 1369 (68.1%) had vertical banded gastroplasty (VBG, or “stomach stapling”), and 265 (13.2%) underwent gastric bypass. The decision about type of surgical procedure was presumably made by providers at the clinical site of the patient’s surgery, though this is not made explicitly clear in the article. Patients in the control group received “the customary treatments for obesity at their centers of registration.” The investigators describe that in some cases this meant lifestyle advice, while in others it meant no treatment whatsoever. Patients were followed for up to 20 years after enrollment.