PARIS — On top of helping obese patients with diabetes achieve their short-term weight and glycemic goals, bariatric surgery may be linked to improved overall cardiometabolic health years later, a retrospective cohort study found.
The cumulative incidence of all-cause mortality, coronary artery events, cerebrovascular events, heart failure, nephropathy, and atrial fibrillation was 30.8% at eight years for patients who underwent metabolic surgery and 47.7% for controls who only got usual care (adjusted HR 0.61, 95% CI 0.55-0.69).
Surgery’s apparent clinical benefit was reinforced by each individual component of the primary endpoint, along with the secondary outcome of combined MI, ischemic stroke, and mortality. Of note, all-cause mortality alone was reduced by approximately 40% (10.0% vs 17.8%, adjusted HR 0.59, 95% CI 0.48-0.72), according to Ali Aminian, MD, of the Cleveland Clinic.
He presented the study at a late-breaking trial session here at the annual European Society of Cardiology meeting. A detailed report was also published online in JAMA.
“We speculate that the lower rate of MACE [major adverse cardiovascular events] after metabolic surgery observed in this study may be related to substantial and sustained weight loss with subsequent improvement in metabolic, structural, hemodynamic, and neurohormonal abnormalities,” Aminian’s team wrote.
This is supported by the surgical cohort losing over 20 kg (44 lbs) more in weight over controls, their 1.1% greater reduction in HbA1c levels, and a lesser need for medications to treat diabetes and cardiovascular diseases over a median 3.9 years of follow-up, the authors continued.
“I think it’s encouraging when we get people to lose weight — [bariatric surgery] is obviously a fairly extreme way to get it done, but weight loss in the diabetic patient with obesity actually results in a very large reduction in morbidity and mortality,” said senior investigator Steven Nissen, MD, of the Cleveland Clinic, in an interview.
“In 2019, for obese patients with diabetes, what is the best treatment option? The results from drug studies, although of relatively high quality, suggest limited effect on long-term macrovascular outcomes,” according to JAMA Deputy Editor Edward Livingston, MD, a surgeon at UCLA, in an accompanying editorial.
“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,” he said.
The observational study is not the first to report a significant association between bariatric surgery and lower risk of mortality and other complications of diabetes. However, it is notable for showing this in patients with more moderate obesity (BMI 45.1 and 42.6 in surgical and non-surgical cohorts, respectively).
Additionally, only those who underwent contemporary metabolic surgeries in 1998-2017 were counted: Roux-en-Y gastric bypass (63%), sleeve gastrectomy (32%), adjustable gastric banding (5%), and duodenal switch in the remaining few.
“Currently available studies have examined a limited number of cardiovascular outcomes, studied patients at low-to-moderate risk, included primarily patients with severe obesity, and in some studies included patients who underwent surgical procedures no longer commonly performed,” according to Aminian and colleagues.
For the study, 2,287 obese adults with type 2 diabetes who underwent metabolic surgery within the Cleveland Clinic Health System (Ohio or Florida centers) were matched 1:5 to nonsurgical patients. After matching, the two groups generally shared similar baseline characteristics: just under two-thirds were women, and median age was around 53 years.
“The difference to prior studies is that these patients were well matched also regarding underlying comorbidities and to some degree also medication use. To my knowledge, no studies [have been] able to match patients to such a granular level,” commented Adrian Billeter, MD, PhD, of Universität Heidelberg in Germany.
On the other hand, Livingston argued that the matching could have been even more precise; he cited the slightly younger age of the surgical arm as an example (52.5 vs 54.8 years).
“Despite careful propensity matching, these sorts of imbalances always persist in observational studies, highlighting the limitations of interpreting comparisons made between groups in such studies,” according to the editorialist.
The study’s design therefore leaves room for potential residual confounding in the analysis. The dataset may also have been subject to coding errors.
This means the results should be confirmed in further randomized trials, the investigators acknowledged.
In the meantime, Billeter said that the findings confirm prior studies (including a recent meta-analysis by his own group).
“Therefore, the impact should be that metabolic surgery should play a much more central role, I would even propose the primary therapy for patients with metabolic diseases and a BMI >30 kg/m2,” he told MedPage Today in an email.
“Unfortunately, metabolic surgery still remains vastly underutilized and general practitioners, endocrinologists, and patients need better and clear[er] information about the health benefits of surgery,” according to Billeter. “They mainly need to know how dangerous obesity and metabolic diseases are!”
The study was supported in part by a Medtronic grant.
Aminian and Livingston disclosed no conflicts.