The Utah Obesity Study has provided the first prospective, long-term controlled trial on the effects of gastric bypass surgery. The trial discovered that the cardiometabolic improvements associated with recent gastric bypass surgery also persist over long periods of time.
Of the 1,156 morbidly obese participants the Utah Obesity Study, 418 underwent gastric bypass surgery. An additional 417 patients sought to undergo the bariatric procedure but were unable to do so, primarily because of insufficient health insurance. Another 321 patients from the Utah Health Family Tree program were selected to function as community controls.
Doctors followed-up with patients in the Utah Obesity Study for six years. At the end of the follow-up period, patients who had undergone gastric bypass surgery maintained significant total weight loss as well as significant improvements in metabolic and cardiovascular factors compared to the control group, who did not undergo the surgery.
Physical examinations were conducted of all the patients at baseline — the start of the study — then at two years and again at six years. Exams included a wide variety of tests, including interviews with a physician and detailed medical history; submaximal exercise treadmill test and electrocardiogram; resting electrocardiograms and echocardiograms; pulmonary function; limited polysomnography; resting and exercise blood pressure; anthropometry; resting metabolic rate; urinalysis; comprehensive blood tests; and questionnaires analyzing the diet, exercise, and quality of life of the study participants. According to Dr. Ted D. Adams of the University of Utah in Salt Lake City, the six-year follow up with patients was “excellent,” with a 97% rate.
“In the surgical group, nearly all of the clinical measures improved significantly between the baseline and 2-year exams, and they remained significantly improved, compared with baseline at 6 years,” said Dr. Adams. The control groups made far less improvement than those who underwent the surgery, however: “The clinical variables in the combined control groups changed minimally if at all over the 6-year period,” continued Dr. Adams.
The group undergoing surgery showed significant weight loss that persisted throughout the six-year follow up, displaying a total weight reduction of 35 percent at two years out and 28 percent at six years out. In contrast, Dr. Adams noted, the control group displayed minimal weight loss.
The surgery group also fared better in diabetes remission at 75 percent at the six year mark, while the combined control groups were at 1 percent. At the end of the six-year follow-up, incidence of diabetes was at 2 percent for the surgery group and 16 percent for the non-surgery group.
Patients who received surgery appeared to display better cardiovascular health, with cardiac morphology measures being significantly improved just six months after surgery. Echocardiography results demonstrated reduced left atrial volume and left ventricular mass, both factors that could reduce the risk of heart failure related to obesity in the long term. Meanwhile, Dr. Adams reported that the control group displayed increased left atrial volume.
Additional improved health measures displayed by the group receiving gastric bypass surgery included reductions in waist circumference, heart rate, triglycerides, insulin resistance, systolic blood pressure, and low-density lipoprotein cholesterol that persisted through the end of the follow-up period. Higher levels of high-density lipoprotein cholesterol were also reported in the surgery group.
Dr. Adams stated that the results only support previous research on the benefits of bariatric surgery in improving health conditions related to being overweight. The findings will continue to provide insights into the benefits of the surgery and their improvements in the long term.
Dr. Adams did not disclose any conflicts of interest.