Weight-loss surgery in obesity, diabetes may expedite CV event reduction vs. usual care
Patients with obesity and diabetes who underwent metabolic surgery may have to lose less weight to reduce the risk for major adverse CV events compared with those who did not undergo surgery, researchers found.
“The interesting and provocative finding is that only about 10% of weight loss in the surgical group was associated with a decrease in [major adverse CV events], but you really had to obtain a 20% weight loss in the nonsurgical group to achieve a similar benefit,” Cardiology Today Editorial Board Member Steven E. Nissen, MD, MACC, chief academic officer of the Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute and Lewis and Patricia Dickey Chair in Cardiovascular Medicine at Cleveland Clinic, told Healio.
Nissen added that despite a growing evidence base showing the benefits of metabolic surgery in this patient population, it is currently performed in a relatively modest number of patients.
“We think — and I will tell you as a cardiologist — that we’re not doing this in enough patients,” Nissen said in an interview. “I send people with heart disease to our metabolic surgeons because of our findings that it reduces major adverse cardiovascular events. Now that we see these differences, perhaps we ought to be a little quicker on the trigger. ... Medical weight loss works in only a very small number of people. Many try and few succeed. Surgical weight loss works in virtually everybody.”
Surgery vs. usual care
Ali Aminian, MD, director of the Bariatric and Metabolic Institute at Cleveland Clinic, and colleagues performed a secondary analysis of an observational matched cohort study previously published in JAMA and presented at the European Society of Cardiology Congress in 2019. As Healio previously reported, metabolic surgery for patients with obesity and type 2 diabetes was linked to lower incidence of major adverse CV events compared with nonsurgical methods of metabolic management.
For this analysis, researchers analyzed data from 7,201 patients (median age, 55 years; 66% women; median BMI, 42.7 kg/m2). Among the cohort, 1,223 patients underwent metabolic surgery (median age, 53 years; 68% women; median BMI, 44.5 kg/m2) and 5,978 patients did not undergo surgery and were treated with usual care (median age, 55 years; 65% women; median BMI, 42.4 kg/m2).
“Weight loss is something that a very large portion of Americans are attempting to do with varying levels of success,” Nissen said. “There has been conflicting information about how much weight loss do you really need to make a difference. There’s also controversy about whether it makes a difference how you get there.”
Outcomes of interest were all-cause mortality and extended major adverse CV events, defined as first occurrence of coronary artery events, cerebrovascular events, HF, nephropathy, atrial fibrillation and all-cause mortality. Patients were followed up for a median of 4.9 years.
Within 8 to 18 months after the index date, the median maximum weight loss in the surgery group was 27.3% compared with 2.8% in the nonsurgical group.
The positive effects that resulted from metabolic surgery persisted after adjusting for weight-loss amounts.
The risk for major adverse CV events decreased with approximately 10% of weight loss with surgery compared with 20% in those treated with usual care after considering weighted estimates from a diverse set of models. The threshold for benefit for all-cause mortality was observed with 5% weight loss in the surgery group vs. 20% in the nonsurgical group.
“There has been a lot of discussion over a long period of time about whether metabolic surgery does more than simply induce weight loss,” Nissen said in an interview. “When you bypass part of the gut, you change certain hormonal factors. There are a lot of hormones secreted by the gut, and they’re not terribly well understood. You change the gut microbiome. You do all these things, so it looks like there may be some weight-independent effects of metabolic surgery and that’s why it takes less weight loss with surgery to get a similar benefit.”
Need for a randomized controlled trial
More research is needed in this area, particularly a randomized controlled trial. Nissen said several researchers are currently preparing a proposal for an NIH-sponsored randomized controlled trial comparing standard of care, including medical weight loss and diabetes management, with diabetes management with medicine and metabolic surgery.
“It’s going to be a very large, very expensive study if the NIH will fund it, and it will be the definitive answer,” Nissen told Healio. “We must do this. Without a [randomized controlled trial], we will not get payers and patients to buy into this. Surgery is not a small undertaking, although it is done laparoscopically now. ... Nonetheless, we have to have a randomized controlled trial to make the case.”
For more information:
Steven E. Nissen, MD, MACC, can be reached at firstname.lastname@example.org.