Medical cannabis encompasses a wide spectrum of products, including dried flowers, oils, and edibles that contain bioactive compounds such as cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC).
Medical cannabis was legalized in Australia in November 2016 and approved for managing chronic pain, anxiety, insomnia, and sleep disturbances. In addition, medical cannabis may be used to treat chemotherapy-induced vomiting and multiple sclerosis-associated spasticity.
Given the vast range of medical conditions being treated with medical cannabis and the wide array of products and dosages available, cannabis as a medicine is becoming increasingly prevalent.
However, data from randomized controlled trials (RCTs) on the medical benefits of cannabis use are limited, and studies evaluating patient-reported outcomes using validated QoL measures could increase the body of evidence on the efficacy and safety of cannabis use and inform policy-making and strategy development for improving the health-associated QoL of patients.
About the study
In the present retrospective case series study, researchers investigated the potential medical benefits of cannabis treatment concerning health-associated QoL among Australians.
The study was conducted at Emerald clinics located in various locations on the Australian continent. The participants received treatment at the clinics for any health condition from December 2018 to May 2022 and were followed up every 45 days (mean) for 15 follow-ups. The study exposure was medical cannabis, with cannabinoid content and product type decided by the treating physician.
The main study outcome was improving health-associated QoL, evaluated using the 36-component Short Form Health Survey (SF-36) questionnaire.
Cannabis use was clinically justified, including reasons for the inappropriateness of the Australian Register of Therapeutic Goods products for the treatment and the exhaustion of other therapies for the clinical indication.
Individuals with carboxy-THC (THC-COOH)-positive urine samples, pregnant and/or lactating individuals, and individuals with serious cardiovascular diseases or serious disorders of mental health, including psychosis history and/or suicidal ideation, were not administered cannabis.
Data were collected from December 2018 onward and are ongoing, with every finding obtained as of 5 May 2022 recorded. Conventional ordinary least squares regression modeling was performed, adjusting for covariates such as medications, comorbidities, age, sex, and work status.
Among 3,148 participants, the mean age was 56 years; 1,688 (54%) were female, and 820 (30%) were employed. Individuals received cannabis treatment most frequently for chronic pain (n=2,160, 69%), cancer pain (n=190, 6.0%), anxiety (n=132, 4.2%), and insomnia (n=152, 4.8%).
Post-treatment initiation, patients reported significant improvements from baseline for all SF-36 domains, most of which were sustained over time.
After controlling for potential confounders in a regression model, treatment with medical cannabis was associated with an improvement of 6.6 to 18 points in SF-36 scores, depending on the domain.
Effect sizes were small to moderate in magnitude, ranging from 0.2 to 0.7. On average, the participants consumed 6.6 medications daily before cannabis therapy.
The most commonly used medications were simple analgesics (n=1,703, 54%), opioid analgesics (n=1,523, 48%), antidepressants (n=1,401, 45%), benzodiazepines (n=1,084, 34%), and gamma-aminobutyric acid (GABA) analogs (n=693, 22%).
Before cannabis treatment, apart from the mental well-being domain (mean 54), the mean scores for all SF-36 domains were below the 50% mark on their respective scales: 40, 30, 41, 14, 28, 37, and 30 for general health, bodily pain, physical functioning, role-physical, role-emotional, social functioning, and vitality, respectively.
Concerning monthly prescriptions, CBD-dominant therapies, balanced therapies, and THC-dominant therapies accounted for 80%, 7.50%, and 13% of prescriptions, respectively. Most patients were orally administered cannabis in oils (90%, 14,779 individuals) and capsules (3.8%, 631 individuals).
Only 244 individuals inhaled dried flowers, and 168 were administered combined dried flower inhalation and oil therapy.
For balanced therapy, equivalent CBD and THC doses of 19 mg (mean) were prescribed daily. For cannabidiol-dominant therapy, the mean CBD and THC doses were 97 mg and 9.0 mg, respectively, and for tetrahydrocannabinol-dominant therapy, the corresponding doses were 5.0 mg and 36 mg, respectively.
The mean daily cannabidiol dose elevated from 51 mg at the initial follow-up to 72 mg at the next follow-up and was continued after that.
Contrastingly, the mean daily tetrahydrocannabinol dose was increased steadily, from 7.0 mg at the initial follow-up to 26 mg at the last follow-up, after 675.0 days of initiating treatment. Concerning SF-36 questionnaire domains except role-physical and physical functioning, balanced products were more effective than THC- and CBD-dominant products.
CBD-dominant products improved the role-physical scores most effectively, whereas THC-dominant products were most effective in improving physical functioning. 2,919 adverse events (AEs) were documented, of which 1,905, 922, and 86 were mild, moderate, and severe, respectively, and two serious AEs were reported.
The most common AEs were sleepiness and/or sedation, xerostomia, tiredness and/or lethargy, dizziness, concentration difficulties, nausea, diarrhea, feeling high, an increase in appetite, anxiety, and headaches.
Overall, the study findings showed that medical cannabis use resulted in sustained improvements in all SF-36 domains assessing health-associated QoL.
AEs were common but rarely serious, indicating that medical cannabis should be cautiously prescribed based on patient profiles.
- Arkell, T. et al. (2023) “Assessment of Medical Cannabis and Health-Related Quality of Life”, JAMA Network Open, 6(5), p. e2312522. doi: 10.1001/jamanetworkopen.2023.12522. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2804653