Metabolic surgery associated with lower risk for MACE in obese adults with type 2 diabetes

Patients with diabetes and obesity who had metabolic surgery were matched in a 1:5 ratio to those who received usual care, with incidence of a major cardiovascular event (MACE) as the primary outcome.

Risk for an incident major adverse cardiovascular event (MACE) was lower in obese patients with type 2 diabetes who had metabolic surgery than in those who did not, according to a recent study.

Researchers used data from the Cleveland Clinic Health System to perform a retrospective cohort study examining the relationship between metabolic surgery and incident MACE in patients with type 2 diabetes and obesity. Patients with diabetes and obesity who had metabolic surgery were matched in a 1:5 ratio to those who received usual care. The primary outcome was incidence of extended MACE, defined as first occurrence of all-cause mortality, coronary artery events, cerebrovascular events, heart failure, nephropathy, and atrial fibrillation. Prespecified secondary outcomes were a three-component MACE, which included myocardial infarction, ischemic stroke, and mortality, and the six individual components of extended MACE. Results of the study, which was funded in part by an unrestricted grant from Medtronic, were published by JAMA on Sept. 2.

All patients at the Cleveland Clinic with a diagnosis of type 2 diabetes from Jan. 1, 1998, and Dec. 31, 2017, were considered for the study. A total of 2,287 patients who had metabolic surgery and 11,435 control patients who did not were followed through December 2018. Median age was 52.5 years versus 54.8 years, respectively, and body mass index was 45.1 kg/m2 versus 42.6 kg/m2. Women made up 65.5% of the surgical group and 64.2% of the nonsurgical group. Overall median duration of follow-up was 3.9 years.

Three hundred eighty-five patients in the surgical group and 3,243 in the nonsurgical group developed extended MACE by the end of the study period, with a cumulative incidence at eight years of 30.8% versus 47.7% (P<0.001) and an adjusted hazard ratio of 0.61 (95% CI, 0.55 to 0.69). Statistically significant differences in favor of metabolic surgery were seen for all of the secondary outcomes. One hundred twelve patients in the surgery group and 1,111 patients in the nonsurgical group died during follow-up, with a cumulative incidence at eight years of 10.0% versus 17.8% and an adjusted hazard ratio for all-cause mortality of 0.59 (95% CI, 0.48 to 0.72).

The researchers noted that causality cannot be assumed, that different metabolic procedures were not compared, and that causes of death could not be determined, among other limitations. They concluded, however, that metabolic surgery is associated with significantly lower risk for incident MACE in obese patients with type 2 diabetes versus nonsurgical management. They called for randomized clinical trials to confirm their findings, since their study was observational.

An accompanying editorial said that the study results should be interpreted with caution, given its limitations, and noted that patients who are willing to undergo a major procedure like metabolic surgery are usually more motivated to improve their health than people who do not choose this procedure.

“In 2019, for obese patients with diabetes, what is the best treatment option?” the editorialist asked. “When balancing the imperfections in the evidence for both medical and surgical treatment of diabetes, the many benefits associated with bariatric surgery-induced weight loss suggest that it should be the preferred treatment option for carefully selected, motivated patients who are obese and have diabetes and cannot lose weight by other means.”