Bariatric surgery improves risk factors but beware complications

Half of mild to moderately obese patients with poorly controlled type 2 diabetes who underwent gastric bypass surgery achieved diabetes management goals compared with less than one-fifth of counterparts who received lifestyle and medical management. But the bypass group also experienced more adverse events in the study, which was published online June 5 in JAMA.

Both obesity and diabetes are risk factors for cardiovascular events. Sustained weight loss has been shown to improve diabetes control, but it is difficult to maintain over time. Medications also help to reduce risk but some patients fail to achieve the goals set by the American Diabetes Association (ADA). Those goals are hemoglobin A1c (HbA1c) of less than 7 percent, low density lipoprotein (LDL) cholesterol of less than 100 mg/dL and systolic blood pressure of less than 130 mm Hg.

Sayeed Ikramuddin, MD, of the surgery department at the University of Minnesota in Minneapolis, and colleagues conducted the Diabetes Surgery Study to compare outcomes in patients who underwent Roux-en-Y gastric bypass to an intensive lifestyle modification-medical management intervention in patients with a body mass index (BMI) between 30 and 39.9 and diabetes type 2. To be included in the study, patients also needed to have HbA1c level of 8 percent or higher and serum C peptide level higher than 1 ng/mL.

The primary composite endpoint was the three targets set by the ADA, with follow-up at one year.  “The rationale for these endpoints is that achieving a HbA1c of 7.0 percent or less protects against vascular complications of type 1 diabetes,” Ikramuddin et al explained. “Decreasing LDL cholesterol and blood pressure reduce the risk of macrovascular events in populations of patients with diabetes.”

From a pool of 2,648 candidates at four centers in the U.S. and Taiwan, they enrolled 120 patients between 2008 and 2011. Sixty patients were randomized to each treatment group. The bypass group also followed the lifestyle intervention protocol and medication programs in addition to surgery, with some accommodations for postsurgical recovery.

Overall, the patients had a mean BMI of 34.6 and mean HbA1c of 9.6 percent. Baseline characteristics were similar between the two groups.

At one year, 49 percent of the bypass group achieved the primary composite endpoint compared with 19 percent of the lifestyle-medical management group. The bypass group lost a mean 26.1 percent in weight vs. 7.9 percent for the lifestyle-medical management group. Patients in the bypass group used on average three fewer medications to manage glycemia, dyslipidemia and hypertension than the lifestyle-medical management group.

But the bypass group also had 22 serious adverse events, including complications that led an anoxic brain injury in one patient, while the lifestyle-medical management group had 15.

“Patients in the gastric bypass group experienced 50 percent more serious and 55 percent more nonserious adverse events than did those in the lifestyle-medical management group,” they wrote, observing that all surgeons in the study were experts. “[E]ven in the hands of experienced surgeons serious complications occur at a modest rate.”

Nutritional deficiencies were higher in the bypass group, too.

“This study provides an indication of the potential benefit as well as the risks of adding gastric bypass to best lifestyle and medical management for diabetes,” Ikramuddin et al wrote. “However, to determine the long-term cardiovascular effects of bariatric surgery would require a large-scale, multiinstitutional study.”

Bruce M. Wolfe, MD, Jonathan Q. Purnell, MD, both of the Oregon Health and Science University in Portland, and Steven H. Belle, PhD, of the University of Pittsburgh, described the complications reported in the bypass group as “problematic.” In their accompanying editorial, they emphasized the need to determine the prevalence and severity of long-term complications and other long-term safety issues.

The study by Ikramuddin and colleagues improved on previous studies, they continued, by using more than one center and more than one surgeon, and by focusing on a single, standardized surgical technique. “This study design overcomes the limitations of prior randomized trials of bariatric surgery that lacked these features and had outcomes less generalizable than those reported by Ikramuddin,” they wrote.