Bariatric surgery linked to markedly decreased stroke risk

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Obese people who had 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, a Canadian study found.

Using Mariner, a national all-payer claims database, Dr Amin Andalib 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 three and five 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 said. “In fact, given the true population-level nature of our observational cohort study along with a very long follow-up period – median of seven 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 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 will convince or sway those individuals who suffer from obesity and metabolic syndrome who remain reluctant to have such a literally lifesaving metabolic intervention.”

In performing the study, the researchers identified a total of 96,094 bariatric surgery patients and 1,533,725 controls. Patients fitted 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 one year, a 56% reduction after three years, and a 49% reduction after five 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 randomised trial that while it may require a tedious multicentre and perhaps international effort to carry out, the impact could be monumental in improving access to surgery by healthcare providers and insurance companies.”

Dr Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in New York City, who was not involved with the study, 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 said. “Bariatric surgery is the most under-utilised modality we have. Insurance in the United States frequently places many barriers. There is still a bias that blames the patient.”

Roslin added that “more patients should demand access and the right to have surgery and not tolerate exclusions and plans on the exchanges that deny coverage”.




See also from the MedicalBrief archives:

Immense health gains from bariatric surgery, say specialists


Bariatric surgery reduces heart risk and diabetes


Bariatric surgery improves obese adolescents' health



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