Prescriptions of medical cannabis have been on the rise in a growing number of countries around the world for a diverse range of conditions and symptoms. Medical cannabis is now utilised with significant frequency for chronic pain conditions in several countries, including the US and Canada.
In fact, chronic pain is the most reported reason for medical cannabis use around the world. Whilst there is growing evidence from randomised controlled trials and observational studies there is a need for further expert guidance on how to dose and administer medical cannabis safely and effectively.
A recent prospective observational study enrolled orthopaedic chronic pain patients to assess the efficacy of medical cannabis and the products’ effects on prescription drug use and side effects. Participants received cannabis education from their physician at the time of certification and purchased products from state-licensed cannabis retailers.
Design and Methods of the Study
A total of 468 patients were recruited from the Rothman Orthopaedic Institute, a large practice in Philadelphia, Pennsylvania. Chronic pain diagnoses varied based on the referring provider’s discretion and included chronic low back pain [N=257], multifaceted pain (e.g., fibromyalgia and neuropathies) [N=111], neck pain (N=63), and joint pain (shoulder, hip, knee) [N=37].
The initiation of this study coincided with the implementation of Pennsylvania’s medical cannabis program – therefore, data regarding patients’ previous experience with cannabis were not collected. Based on data available from US states where cannabis is still illegal, researchers note that up to 7.4% of the participants may have been daily cannabis users before enrolling in the study.
Measures
A number of methods were used to measure the analgesic (pain-relieving) effects of cannabis (Visual Analog Scale; Patient-Reported Outcomes Measurement Information System); Quality of Life; Patterns, frequency, perceived efficacy and side effects of cannabis use were measured using a purpose-built survey, the Inventory of Medical Cannabis Use (iMCU).
Researchers also monitored prescription drug use for a 6-month period before, and a 6-month period following enrolment in Pennsylvania’s medical cannabis program. Opioid use was measured using morphine milligram equivalents (MME). Daily opioid consumption was normalized by dividing each patient’s total MME prescribed in a 6-month period by the number of days that the patient had an active opioid supply.
Results of the Study
A subset of the total patient sample (N=328) completed all or part of the Inventory of Medical Cannabis Use (iMCU). Fifty per cent of participants who completed the iMCU used cannabis at least once daily (the most commonly reported frequency of cannabis use was two to three times per day), and 70% either agreed or strongly agreed that cannabis alleviated their primary symptom of pain.
At their first follow-up (3 months), 59% (N=177) of participants reported using sub-lingual cannabis products, while 60% (N=139) reported vaporising cannabis (some patients used both sublingual and vaporised products). While all participants were asked to report the THC content of their medical cannabis products, only 23% were able to do so for inhalation products, and 29% for oral products.
Effects of Medical Cannabis on…
Pain Levels
The primary outcome of this study was VAS pain scores. These were taken at follow-up sessions 3, 6, and 12 months following the initiation of therapy. VAS pain was seen to reduce significantly at each of these follow-ups. From an average pain score of 6.7 at initiation, pain scores fell to 5.2 at the 3-month follow-up. Average pain scores then remained consistent across the remaining follow-ups.
Furthermore, a significant majority of participants (69%) reported reducing or ceasing their use of benzodiazepines – prescription medications that are routinely prescribed for chronic pain. This suggests that cannabis may have been effective at reducing pain levels.
Quality of Life
Patients with chronic pain conditions consistently report reduced quality of life. Previous studies have suggested that medical cannabis can be useful in improving quality of life in those with chronic pain – and the results of the present study support these findings. Average patient quality of life scores increased from 0.61 at treatment initiation to 0.65 at first follow-up. Scores then remained consistent for month 6 and month 12 follow-ups. This improvement was considered by the researchers to be significant.
Physical and Mental Health
Similar improvements were seen in global physical health and global mental health scores. Average global physical health scores increased from 38.3 at baseline to 41.4 at the first follow-up; no significant difference was seen between month 3 and months 6 and 12 follow-ups. Average global mental health scores increased from 45.4 at baseline to 47.2 at month 3 follow-up; again, no significant difference was seen between month 3 and months 6 and 12 follow-ups.
Opioid Use
Usage of opioid data was available for 358 of the participating patients. Prior to the initiation of medical cannabis therapy, the 6-month total opioid use was an average of 3021 MME. Following the initiation of cannabis therapy, the mean 6-month total opioid use fell to an average of 2314 MME. Therefore, the initiation of cannabis therapy was associated with a 23.4% reduction in the 6-month total opioid prescription.
Medical cannabis was also associated with a reduction in normalised daily opioid use: falling from an average of 31.26 MME to 21.82 MME (a 30.2% reduction).
Researcher Conclusions
The authors conclude that the results of this study support the use of cannabis as an analgesic and drug-sparing therapy. It is noted that, in patients with chronic musculoskeletal noncancer orthopaedic pain, medical cannabis was associated with a reduction in pain, improved mental and physical health, as well as quality of life.
In the patient sample assessed in this study, these effects were seen to occur within three months of regular cannabis use and appeared to plateau thereafter. These results also “show an objective association between the initiation of cannabis therapy and the reduction of both opioid and benzodiazepine prescriptions.
Finally, the authors note that the majority of patients experienced therapeutic benefit from cannabis with infrequent-to-moderate cannabis use and were able to self-titrate their dose in a manner that produced beneficial effects in the absence of intoxication.
