Bariatric Surgery Tied to 22% Lower 5-Year Stroke Risk

Marlene Busko

June 21, 2021

Dr Michael D. Williams

Patients with obesity who underwent bariatric surgery had 46% lower odds of stroke 1 year later, similar odds of stroke 3 years later, and 22% lower odds of stroke 5 years later, compared with matched control patients, in new research.

Michael D. Williams, MD, presented the study findings (abstract A002) at the annual meeting of the American Society for Metabolic & Bariatric Surgery.

The findings are "very good news," even though the protection against stroke declined further out from the surgery, John D. Scott, MD, scientific program chair of the ASMBS meeting, told this news organization.

The investigators matched more than 56,000 patients with obesity who had bariatric surgery with an equal number of similar patients who did not have this surgery, from a large national insurance database, in what they believe is the largest study of this to date.

Dr John D. Scott

"Any intervention that decreases your risk of [cardiovascular] events is good news," said Scott, a clinical professor of surgery at the University of South Carolina, Greenville, and metabolic and bariatric surgery director at Prisma Health in Greenville, S.C. "And having a 22%-45% chance of reduction in stroke risk is a very worthwhile intervention."

Asked how this would change the way clinicians inform patients of what to expect from bariatric surgery, he said: "I would advise patients that studies like this show that surgery would not increase your risk of having a stroke.

"This is consistent with many studies that show that the risks of all macrovascular events decrease after the comorbidity reductions seen after surgery."

According to Scott, "the next steps might include a prospective randomized trial of medical treatment versus surgery alone for [cardiovascular]/stroke outcomes, but this is unlikely."

Similarly, Williams told this news organization that "I would tell [patients] that surgery is an effective and durable method for weight loss. It also can improve comorbid conditions, particularly diabetes and hypertension."

Even with this study, "I'm not sure it's appropriate to say that bariatric surgery will reduce the risk of stroke," he cautioned.

"However, as we continue to investigate the effects of bariatric surgery, this study contributes to the greater body of knowledge that suggests that reduction in ischemic stroke risk is yet another benefit of bariatric surgery."

The assigned discussant, Corrigan L. McBride, MD, MBA wanted to know if the lower odds ratio at 1 year might be because preoperative patient selection might eliminate patients at high risk of poor cardiovascular outcomes.

Williams, a resident at Rush Medical College, Chicago, replied that it is difficult to eliminate potential selection bias, despite best efforts, but this study shows that he can tell patients: "Having surgery is not going to increases your risk of stroke."

"This is an important study," McBride, professor and chief of minimally invasive surgery and bariatric surgery, University of Nebraska Medical Center, Omaha, told this news organization.

"It is the first large study to show a decreased [or no increased] risk of stroke 1, 3, and 5 years after bariatric surgery compared to matched patients, and it had enough data to look at stroke as a standalone endpoint," McBride said. "It is important too, for patients and their physicians to understand that there is a lower chance of them having a stroke if they have surgery than if they do not."

"Important," "Good News" for Stroke Risk After Bariatric Surgery

The impact of bariatric surgery on remission of type 2 diabetes is well known, Williams noted, and other studies have reported how bariatric surgery affects the risk of major adverse cardiovascular events — a composite of stroke, myocardial infarction, coronary artery disease, and all-cause death — including a study presented in the same meeting session.

However, a very large sample size is needed to be able to demonstrate the effect of bariatric surgery on stroke, since stroke is a rare event.

The researchers analyzed data from the Mariner (PearlDiver) all-payer insurance national claims database of patients in the United States.

They matched 56,514 patients with a body mass index over 35 kg/m2 and comorbidities or a BMI of more than 40 who underwent sleeve gastrectomy or Roux-en-Y gastric bypass during 2010-2019 with 56,514 control patients who did not undergo bariatric surgery.

A year after bariatric surgery, patients in that group had a lower stroke rate than patients in the control group (0.6% vs. 1.2%), and they had close to 50% lower odds of having a stroke (odds ratio, 0.54; 95% CI, 0.47-0.61).

Three years after bariatric surgery, there were 44,948 patients in each group; the rate of stroke was 2.1% in the surgery group and 2.2% in the control group, and there was no significant difference in the odds of having a stroke (OR, 0.96; 95% CI, 0.91-1.00).

Five years after bariatric surgery, there were 27,619 patients in each group; the stroke rate was lower in the bariatric surgery group than in the control group (2.8% vs 3.6%), but reduced odds of stroke was not as great as after 1 year (OR, 0.78; 95% CI, 0.65-0.90).

Williams has no relevant financial disclosures. McBride and Scott disclosed that they are speakers/trainers/faculty advisers for Gore. Scott is also a consultant for C-SATS (part of Johnson & Johnson).

This article originally appeared on, part of the Medscape Professional Network.


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