RATIONALE

RATIONALE

Bariatric surgery leads to weight loss of 25–35% of body weight (usually at least 15 /uni00A0 kg) after 1 year, and sustained weight loss maintenance at 15–25% after 20 years. Additional benefits are that most or all of the obesity-related diseases improve as weight is lost and even independently of weight loss. Quality of life improves. A number of randomised controlled trials (RCTs) have reported on the outcomes of bariatric surgery versus intensive lifestyle interventions, and all favour surgery . The longest follow-up in an RCT is 5 years. However, the non-randomised Swedish Obese Subjects (SOS) study has now shown sustained weight loss and improvement in obesity- related disease up to 20 years after surgery . In this study 2010 patients who chose to have surgery were compared with 2037 controls who did not. When the SOS study was conceived in 1987 all surgery was done by laparotomy and it was considered unethical to attempt to randomise patients between best medical therap and bariatric surgery . All had best medical care throughout and follow-up was better than 99%. The SOS study was among the first to demonstrate that bariatric surgery also leads to survival benefit. The primary end point was overall mortality and a significant di ff erence was found at a mean follow-up of 10 years. Many other studies have now found similarly , including one of nearly 8000 operated patients from Utah. The Utah study was the first large study to show improved survival after gastric bypass surgery compared with matched population controls. The SOS study also reported a low dence of both microvascular and macrovascular complications at 15 years of follow-up in the surgical group . The Swedish registry (SOREG) data indicate lower mortality within only 3–4 years after surgery in patients with type 2 diabetes. Both the SOS and Utah studies have shown that bariatric surgery also e ff ectively reduces cancer risk in large patient cohorts.