Study: Cannabis Users Use Less Opioids When Recovering from Neck Fusion Surgery

The findings on neck fusion surgery come via researchers at the University of Connecticut School of Medicine.

There are already a number of studies showing how cannabis use can curb opioid use, in relation to myriad ailments and conditions. Now, a new study sheds light on a major neck surgery, similarly finding that cannabis consumers ultimately used fewer opioids in recovery than non-consumers.

A team of researchers from the University of Connecticut School of Medicine conducted the study, published in the North American Spine Society Journal

Expanding Literature on Cannabis, Pain and Orthopedics

The research specifically investigates anterior cervical discectomy and fusion (ACDF). The procedure involves the removal of all or part of a damaged disc in the spine, effectively relieving spinal cord or nerve root pressure in the neck and alleviating related pain, weakness, numbness and tingling.

The study introduction nods to the “growing evidence to suggest that cannabis use may positively impact opioid consumption.” It also cites the growing body of literature surrounding cannabis and its potential medical benefits, though it notes that there are only a handful that explore its potential as it pertains to orthopedics.

Researchers assessed the use of opioids following ACDF surgery utilizing a retrospective case-control design. Using PearlDiver, they examined patients who underwent a single-level ACDF between January 2020 and October 2020. 

Patients were then placed in the study group if they had a “previous diagnosis of cannabis use, dependence or abuse.” Patients under the age of 18 or those who had filled an opioid prescription within three months of their procedure. Researchers formed a control group to match on age, gender, the Charlson comorbidity index (which predicts the 10-year mortality for patients with a range of relating disease) and had “no diagnosis of cannabis use.”

A total of 1,339 patients were included in each group. 

Cannabis Users Tend to Use Less Opioids Post-Op

Overall, fewer patients in the cannabis group filled their opioid prescriptions within three days post-operation, consistent with current literature on cannabis use and need for opioid medication.

More than 7% of patients in the control group filled their initial opioid prescription within three days of surgery, compared to 2.7% in the cannabis use group. There were no differences for patients who filed prescriptions at 30 and 60 days after the procedure, and no patients within the cannabis group filled their initial prescriptions 90 days after the procedure.

In their discussion of the findings, authors also noted that, at 60 days, the control group needed higher doses of opioids than the cannabis group.

“Daily MME [morphine milliequivalent] doses in the cannabis group were below 50 MME for prescriptions filled within 60 days postoperatively whereas the control group was at the 60 MME level at the same time point,” authors state. “The 50 MME threshold is important as studies have suggested that opioid doses above 50 MME per day are significantly associated with an increased risk of opioid related death and/or hospitalization. This suggests that patients using cannabis may be at a reduced risk of opioid dependence than nonusers.”

About 3.1% of the control group filled additional opioid prescriptions, compared to 1.8% of the cannabis group when looking at the total number of patients. Looking only at patients that filled an initial prescription, the cannabis group scored higher, with nearly 34% of the cannabis group and 24% of the control group filling additional prescriptions, though authors said this was not a statistically significant difference. 

There were no differences in the number of prescriptions filled at both 60 and 90 days after the procedure.

Conclusions and Looking Ahead

“In summary, patients who were known to use cannabis filled fewer opioid prescriptions following ACDF procedures and were prescribed lower daily doses than the control group, suggesting that cannabis use may reduce opioid requirements in this population. However, there is a clear need for future studies to investigate the effect that cannabis use may have on postoperative pain control,” the study concludes.

Researchers admit there were inherent limitations, given the use of a large insurance claims database. For one, data were based solely on billable codes which could cause selection bias in the cannabis group “where the accuracy of diagnosis codes surrounding cannabis use is questionable.” This means it’s likely that cannabis use is underrepresented in this study, according to researchers.

The codes were also generic to cannabis and did not distinguish between CBD and THC, which could also significantly alter the effects toward general health and need for opioids. The database was also not designed to indicate how much of a prescription was used after being filled, only if it was being filled in the first place.

Researchers also note the changing climate surrounding cannabis, noting that 15 states implemented laws to partially or fully legalize cannabis from 2010-2020, the period the database covered.

“As the use and perception of marijuana continue to develop, our ability to gather precise data may improve as patients become more forthcoming about their usage, have more access to both medical and recreational products, and receive better education on the advantages and risks of marijuana,” authors write. “These ongoing changes will inevitably affect the reliability of data collection in this field.”

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