Cannabis usage is associated with increased usage of opioids postoperatively, both while in-patient and post-discharge, following posterior lumbar spinal fusion surgery. This is the key finding of a study published in the Global Spine Journal by Andrew Moon (Tufts Medical Center, Boston, USA) et al.
The retrospective study aimed to evaluate the association between preoperative cannabis usage and consumption of opioids for postoperative analgesia.
Patients who underwent one- or two-level posterior lumbar fusion surgery were categorised as cannabis users or non-cannabis users based on preoperative diagnoses of cannabis use. Total morphine equivalent dose was calculated for both in-house opioid consumption and postoperative prescription opioid usage.
Age, American Society of Anaesthesiologists (ASA) score, body mass index (BMI), depression, tobacco use, estimated blood loss (EBL), operating room (OR) time, length of stay (LOS), disposition to rehab, 30-day readmission, in-house opioid consumption and postoperative prescription opioid usage were compared between groups using t-tests.
Of the 220 opioid naïve patients, 29 (13%) patients were identified as cannabis users while 191 (87%) were non-cannabis users.
The study found that there were no significant associations between opioid naïve cannabis usage and ASA score, BMI, tobacco use, EBL, OR time, LOS, disposition to rehab, or readmission. Opioid naïve cannabis users did however have a greater association with depression (31.3% vs 13.7%, p=0.017) and were younger (56.37 years vs. 65.37 years, p<0.001).
Interestingly, cannabis use was associated with a lower Charlson Comorbidity Index (1.38 vs. 2.49, p=0.002) and cannabis users were also found to have increased postoperative prescription opioid usage (2545.41 POST-MED vs. 1379.72 POST-MED, p=0.019).
Speaking to Spinal News International, Moon said: “Cannabis is the most commonly used illicit substance in the United States, and the legality of cannabis usage in the United States continues to expand; a total of 37 states, three territories, and the District of Columbia allow medical use of cannabis products, while 19 states, two territories, and the District of Columbia have passed measures to regulate non-medical use of cannabis in adults.
“Given the ongoing concerns regarding opioid usage and risks of opioid dependence, it is important to consider the potential implications of preoperative cannabis usage on postoperative pain control in patients undergoing lumbar spinal fusion surgery.”