Medicinal cannabis for Australian patients with chronic refractory pain including arthritis.

Objectives: To examine the tolerability and effectiveness of medicinal cannabis prescribed to patients for chronic, refractory pain, with a subset analysis on arthritis.

Methods: This was an interim analysis of the CA Clinics Observational Study investigating self-reported adverse events (AEs) and changes in health-related quality of life (HRQoL) outcomes over time after commencing medicinal cannabis. Patients were prescribed medicinal cannabis by a medical practitioner, containing various ratios of Δ-tetrahydrocannabinol (THC) and/or cannabidiol (CBD).

Results: The overall chronic pain cohort, and specifically the balanced CBD:THC products, were associated with significantly reduced pain intensity scores ( = 0.003, = 0.025), with 22% of patients reporting a clinically meaningful reduction in pain intensity. Patients in the arthritis subset ( = 199) reported significantly reduced pain intensity scores ( = 0.005) overall, and specifically for those taking CBD-only ( = 0.018) and balanced products ( = 0.005). Other HRQoL outcomes, including pain interference and pain impact scores were significantly improved depending on the CBD:THC ratio. Products that contained a balanced ratio of CBD:THC were associated with improvements in the most number of PROMIS-29 domains. Approximately half ( = 364; 51%) of the chronic pain cohort experienced at least one AE, the most common being dry mouth (24%), somnolence (19%) or fatigue (12%). These findings were similar in the arthritis subset.

Discussion: Medicinal cannabis was observed to improve pain intensity scores and HRQoL outcomes in patients with chronic, refractory pain, providing real-world insights into medicinal cannabis' therapeutic potential.