Cannabinoids in the Management of Acute Pain: A Systematic Review and Meta-analysis.

Objective

To synthesize the best evidence surrounding the efficacy of cannabinoids for acute pain in the clinical setting based on subjective pain scores and observed adverse effects.

Design

Systematic review with meta-analysis. Data Sources: PubMed, Embase, Cochrane Databases, and Google Scholar. Eligibility Criteria: English-language randomized-controlled clinical trials comparing cannabinoids with placebo in patients with acute pain. Data Extraction and Synthesis: Study quality was assessed using the Cochrane risk of bias tool. All stages were conducted independently by a team of three reviewers. Data were pooled through meta-analysis and stratified by route of administration. Primary Outcomes and Measures: Patient-reported pain and adverse events (AEs).

Results

Six trials (678 participants) were included examining oral (5 trials) and intramuscular (1 trial) cannabinoids. Overall, there was a small but statistically significant treatment effect favoring the use of cannabinoids over placebo (-0.90, 95% confidence interval [CI] -1.69 to -0.1, i 2=65%, p=0.03). When stratified by route of administration, intramuscular cannabinoids were found to have a significant reduction in pain relative to placebo (-2.98, 95% CI -4.09 to -1.87, i 2=0%, p<0.0001). No difference in effect was observed between oral cannabinoids and placebo (-0.21, 95% CI -0.64 to 0.22, i 2=3%, p=0.34). Serious AEs were rare, and similar across the cannabinoid (14/374, 3.7%) and placebo groups (8/304, 2.6%).

Conclusions

There is low-quality evidence indicating that cannabinoids may be a safe alternative for a small but significant reduction in subjective pain score when treating acute pain, with intramuscular administration resulting in a greater reduction relative to oral. Higher quality, long-term randomized-controlled trials examining whether there may be a role for cannabinoids in treating acute pain are required.