Bariatric Surgery Tied to Decreased Stroke Risk Out to 5 Years

Individuals with obesity who opted for bariatric surgery to reduce their weight appeared to get an added benefit of a markedly reduced risk of stroke, a difference that can be measured as early as a year after undergoing the procedure, researchers reported.

Using Mariner, a national all-payer claims database, Amin Andalib, MD, of McGill University/Montreal General Hospital in Canada, and colleagues determined that among the patients who underwent either sleeve gastrectomy or gastric bypass from 2010 to 2019, the risk of stroke in the first year post-surgery was 0.05% compared with 0.26% for a cohort of similar patients who did not have the surgery (P<0.01).

Reporting the results at the virtual 2021 meeting of the American Society for Metabolic and Bariatric Surgery, Andalib said that the differences continued after both 3 and 5 years:

3 years: 0.13% vs 0.43%, respectively (P<0.01)

5 years: 0.21% vs 0.59% (P<0.01)

“We believe our findings are definitely clinically important,” Andalib told MedPage Today. “In fact, given the true population-level nature of our observational cohort study along with a very long follow-up period — median of 7 years, and up to 11 years — we were able to calculate a long-term 10-year absolute risk reduction for major adverse cardiovascular events that was found to be 5%.”

“This statistic implies that we need to perform bariatric surgery on only 20 patients in order to prevent a composite major adverse cardiovascular event outcome including all-cause mortality and stroke in patients suffering from obesity and metabolic syndrome and up to a decade after surgery,” he continued. “I hope this would convince or sway those individuals who suffer from obesity and metabolic syndrome who remain reluctant to have such a literally life-saving metabolic intervention.”

In performing the study, the researchers identified a total of 96,094 bariatric surgery patients and 1,533,725 controls. Patients fit into the criteria for the study if they had a body mass index (BMI) greater than 40, or greater than 35 with qualifying comorbidities. Similar patients who did not have bariatric surgery were used as controls.

The team performed coarsened exact matching in a 1:1 fashion with logistic regression analysis to determine the effect of bariatric surgery on stroke risk at 1, 3, and 5 years.

In the matching exercise, the researchers were able to pair 95,565 surgery patients with 95,565 patients who did not have surgery. The outcomes were similar, translating to a 64% reduction in strokes after 1 year, a 56% reduction after 3 years, and a 49% reduction after 5 years, Andalib reported.

“Despite the consistently shown long-term protective effects of bariatric/metabolic surgery against hard cardiovascular outcomes including all-cause mortality by studies like ours, access to surgery continues to be poor and impacted by socioeconomic and health provider disparities,” he said. “The findings from our study, among others, can lay the ground for a randomized trial that while it may require a tedious multicenter and perhaps international effort to carry out, the impact will likely be monumental in improving access to surgery by healthcare providers and insurance companies.”

Asked for his opinion. Dr. Abkin, President of Advanced Laparoscopic Surgeons of Morris, LLC, said: “These findings are most clinically meaningful and the methodology is very sound. This is actually how most long-term cohort studies are done.”

“Furthermore, the matched cohort eliminates a potential bias. Here, both raw data and matched cohort data showed a very significant medical benefit for the surgical group.”

“The next question is whether this will increase surgical access and volume. It should, but there is already data about longevity, heart disease, diabetes, cancer, sleep apnea, cataracts, and many other related diseases and comorbid conditions,” he continued. “Bariatric surgery is the most underutilized modality we have. Insurance in the United States frequently places many barriers. There is still a bias that blames the patient.”

Abkin added that “more patients should demand access and the right to have surgery and not tolerate exclusions and plans on the exchange.