By Shereen Jegtvig NEW YORK (Reuters Health) - Bariatric surgery results in substantial weight loss and can turn back some diseases related to obesity, a new study finds. There is some risk of complications, but death rates appear to be lower than previously thought, researchers reported after reviewing about a decade's worth of recent data. They were interested in updating current knowledge about the effectiveness and safety of various types of weight loss surgery, including gastric bypass, adjustable gastric banding (lap banding), vertical banded gastroplasty and sleeve gastrectomy. These surgical procedures are used for people who are severely obese, or moderately obese with serious weight-related health problems. The last time there was a major update of bariatric surgical research was in 2003. "Previous reviews included data from clinical trials and studies published before 2003, but because of advances in technology of bariatric surgery and accumulation of surgeons' experience, information provided in previous reviews is outdated," Su-Hsin Chang told Reuters Health in an email. Chang is an instructor with the Division of Public Health Sciences, Department of Surgery at the Washington University School of Medicine in St. Louis, Missouri and led the new study. "We planned to answer general questions regarding effectiveness and risks of surgical treatment of obesity and which surgical procedure is the most efficacious," Chang said. The results were published in JAMA Surgery. The researchers reviewed 164 studies conducted from 2003 to 2012, which included a total of 161,756 patients. On average, the patients were about 45 years old and almost 80 percent were female. The average body mass index (BMI), a measure of weight relative to height, of patients before surgery was nearly 46. A BMI of 18.5 to 24.9 is considered normal weight and a BMI of 35 or higher is considered obese. Patients' presurgery weight averaged 274 pounds. More than a quarter of patients had diabetes, nearly half had high blood pressure and almost 30 percent had high cholesterol. Seven percent had heart disease and 25 percent had sleep apnea. Chang's group found that patients' BMI dropped by an average of 12 to 17 points within 5 years after surgery. The researchers also found that diabetes, high blood pressure and sleep apnea improved significantly. Between 86 percent and 92 percent of patients with diabetes experienced remission of the disease. The same happened for about 75 percent of those with high blood pressure. High cholesterol and heart disease were rolled back at slightly lower rates, but sleep apnea disappeared or improved dramatically in more than 90 percent of those who had it pre-surgery. Death rates ranged from 0.08 within one month of surgery to 0.31 after 30 days. Complication rates ranged from 10 percent to 17 percent and the proportion of operations that needed to be repeated was 6 percent to 7 percent. Gastric bypass surgeries were the most effective in terms of long-term weight loss, but the procedure had the highest complication rates. Sleeve gastrectomy was almost as effective as gastric bypass. Adjustable gastric bands (lap bands) weren't quite as effective but were the safest. "Weight loss surgery provides substantial effects on weight loss and improves obesity-related conditions in the majority of bariatric patients, although risks of complication, reoperation and mortality exist," Chang said. "The article is very interesting and overdue," Dr. Pratt Vemulapalli told Reuters Health in an email. Vemulapalli is director of bariatric surgery and an associate professor of surgery at the Montefiore Medical Center of the University Hospital for the Albert Einstein College of Medicine in New York. She was not involved in the study. "Those of us doing bariatric surgery have seen this with our own patients and in studies that have been published in the literature but this meta-analysis simply ties that data together and has wrapped the impression like a present in a neat package," she said. Vemulapalli said there are currently about 200,000 weight loss procedures performed each year. She said the most common procedures are the gastric bypass, the sleeve gastrectomy and, to a lesser extent, the adjustable gastric band. "The article itself was very well done, and shows that the surgeons and centers who do surgery know how to do the operations, know which patients to operate on and how to identify and treat complications," she said, "All of this makes for safer surgery." SOURCE: http://bit.ly/1cNdLW6 JAMA Surgery, online December 18, 2013.