Blue Cross Blue Shield of Michigan data helps researchers learn how cannabis use affects bypass surgery patients

Data collected by Blue Cross Blue Shield of Michigan in collaboration with health care providers is helping bridge knowledge gaps in the medical community about the impacts of cannabis use on outcomes after bypass surgery.

Dr. Drew Braet and his colleagues at Michigan Medicine were recently discussing a case where a patient had bypass graft surgery and the graft clotted.* The outlying factor was that the patient was a daily cannabis smoker. This raised a question the team couldn’t answer: Does smoking cannabis affect how blood clots form?

“There was no existing literature on it,” Dr. Braet said.

In Michigan, medical cannabis has been legal since 2008 and recreational cannabis has been legal since 2018. However, there have been few scientific studies conducted to date on its specific impacts. This makes it difficult for medical professionals to help patients understand how cannabis use affects their health, especially when it comes to surgery outcomes. With the prevalence of legal cannabis in the U.S. and its reported use on the rise according to federal data analyzed in the 2021 Monitoring the Future report, Dr. Braet and his colleagues responded to the need for more solid scientific research.*

The team at Michigan Medicine turned to case data from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium, known as BMC2. BMC2 is a collaborative consortium of health care providers dedicated to improving the quality of care and outcomes for cardiovascular patients across Michigan.

The researchers studied the cases and outcomes of more than 11,000 patients who underwent lower extremity bypass procedures from 2014 to 2021. These surgeries are used to move blood around a blocked artery to improve and restore blood flow to the lower leg and foot. About 9% of the patients whose cases were studied had smoked cannabis within the month before their surgery.

“The BMC2 is the perfect data set,” Dr. Braet said. “It has a robust amount of outcome data. We can look at multiple outcomes, including heart attack and stroke. So many other data sets don’t have that.”

Their study, published in Annals of Vascular Surgery, found that patients who reported cannabis use had a higher chance of the graft becoming blocked or obstructed and were 1.25 times more likely to require an amputation one year post-surgery.* These patients were also more likely to use opioids after discharge.

Though the researchers caution that more data is needed, the study offers new information to help patients understand risks and outcomes before vascular surgery. Dr. Braet believes the study will help the scientific and medical communities pursue future research into the impacts of cannabis on the body and help doctors facilitate fact-based conversations with patients.

“Patients ask us all the time about it. We tell them what we know,” Dr. Braet said.

For more information on how Blue Cross is ready to help providers improve outcomes for cardiovascular patients, read this article on mibluesperspectives.com.

*Blue Cross Blue Shield of Michigan doesn’t own or control this website.

Blue Cross Blue Shield of Michigan and Blue Care Network are nonprofit corporations and independent licensees of the Blue Cross and Blue Shield Association.