October 29, 2018
2 min read

Bariatric surgery can halve risk for CV events in type 2 diabetes

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Adults with obesity and type 2 diabetes who underwent bariatric surgery were half as likely to experience macrovascular complications over 4 years, including acute myocardial infarction or stroke, compared with similar patients receiving usual care, according to a retrospective analysis of more than 20,000 patients published in JAMA.

“Several observational studies have provided evidence that bariatric surgery may reduce macrovascular complications of type 2 diabetes when compared with usual medical care, but limitations of these studies include the inability to study contemporary bariatric procedures because of small numbers of patients and unavailability of body mass index measurements for identifying a cohort of nonsurgical matches,” David P. Fisher, MD, of the Permanente Medical Group in Northern California, and colleagues wrote in the study background. “To address these concerns, a study was conducted to test the hypothesis that patients undergoing contemporary bariatric procedures would experience a lower rate of macrovascular events than matched patients with severe obesity and type 2 diabetes who received usual care in four integrated health insurance and care delivery systems in the United States.”

Fisher and colleagues analyzed data from 5,301 adults with severe obesity (BMI ≥ 35 kg/m²) who underwent bariatric surgery between 2005 and 2011. Researchers matched those adults by age, sex, BMI, HbA1c, insulin use, observed diabetes duration and prior health care utilization with 14,934 controls receiving usual care. Mean age for both groups was 50 years; mean baseline BMI was 44.7 kg/m² and 43.8 kg/m², respectively, for the bariatric surgery and control groups. Researchers followed the cohort through September 2015.

Within the bariatric surgery group, 76% underwent Roux-en-Y, 17% underwent sleeve gastrectomy and 7% underwent adjustable gastric banding. Researchers used Cox regression analysis to investigate time to incident macrovascular disease, defined as the first occurrence of coronary artery disease or cerebrovascular events. Secondary outcomes included CAD and cerebrovascular events analyzed separately.

By September 2015, researchers observed 106 macrovascular events among surgical patients, including 37 cerebrovascular events and 78 coronary artery events during a median 4.7 years. Among controls, researchers observed 596 events, including 227 cerebrovascular events and 398 coronary artery events during a median 4.6 years.

The researchers found that bariatric surgery was associated with a lower composite incidence of macrovascular events at 5 years (2.1% vs. 4.3%), for an HR of 0.6 (95% CI, 0.42-0.86). Additionally, bariatric surgery was associated with lower incidence of CAD (HR = 0.64; 95% CI, 0.42-0.99). The between-group difference in cerebrovascular events, however, did not rise to significance (0.7% vs. 1.7%), according to the researchers.

“These findings have strong biological plausibility and are consistent with other research,” the researchers wrote. “Randomized trials have demonstrated that bariatric procedures are more effective than the best-available intensive medical and lifestyle interventions in promoting weight loss, improving glycemic control and serum lipid levels and reducing the need for medications used to control diabetes, hypertension and dyslipidemia.”

In commentary accompanying the study, Adam C. Sheka, MD, of the department of surgery at the University of Minnesota, and colleagues wrote that the results should lead researchers and clinicians to question why bariatric surgery is not as well-accepted as medications for the treatment of type 2 diabetes.

“Even though there appears to be relatively weak evidence supporting aggressive medical management of type 2 diabetes for reducing CV events and mortality, evidence for the benefits of bariatric surgery for improving outcomes is increasing,” Sheka and colleagues wrote. “Yet, access to bariatric surgery is limited by stringent private insurance requirements, lack of Medicaid coverage in some states and high out-of-pocket costs.”

The results suggest that insurance coverage for weight-loss operations should be expanded for appropriate patients, the researchers wrote. – by Regina Schaffer

Disclosures: One of the commentary authors reports he has received grant support from EnteroMedics and Medtronic. The other authors report no relevant financial disclosures.