Cannabis use increases pain after surgery, study shows

Adults who use cannabis have more pain after surgery than those who don't use cannabis, according to a study presented at the Anesthesiology 2022 annual meeting.

"Cannabis is the most commonly used illicit drug in the United States and increasingly used as an alternative treatment for chronic pain, but there is limited data that shows how it affects patient outcomes after surgery," said Elyad Ekrami, M.D., lead author of the study and clinical research fellow of the Outcomes Research Department at Cleveland Clinic's Anesthesiology Institute. "Our study shows that adults who use cannabis are having more—not less—postoperative pain. Consequently, they have higher opioid consumption after surgery."

Researchers analyzed the records of 34,521 adult patients—1,681 of them cannabis users—who had elective surgeries at Cleveland Clinic from January 2010 to December 2020. The cannabis users had used the drug within 30 days before surgery, while the other patients had never used cannabis. The patients who used cannabis experienced 14% more pain during the first 24 hours after surgery compared to the patients who never used cannabis. Additionally, patients who used cannabis consumed 7% more opioids after surgery, which the authors note was not statistically significant, but is likely clinically relevant.

"The association between cannabis use, pain scores and opioid consumption has been reported before in smaller studies, but they've had conflicting results," Dr. Ekrami added. "Our study has a much larger sample size and does not include patients with chronic pain diagnosis or those who received regional anesthesia, which would have seriously conflicted our results. Furthermore, our study groups were balanced by confounding factors including age, sex, tobacco and other illicit drug use, as well as depression and psychological disorders."

Dr. Ekrami noted that additional research is needed to further define cannabis' effects on surgical outcomes. "Physicians should consider that patients using cannabis may have more pain and require slightly higher doses of opioids after surgery, emphasizing the need to continue exploring a multimodal approach to post-surgical pain control," he said.

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