Medicinal cannabis is being prescribed for an increasing range of conditions globally. There is evidence in conditions such as chronic pain, epilepsy, and multiple sclerosis as well as anxiety disorder and insomnia. Whilst we await randomised controlled trials (the gold-standard of medical evidence) it is important to examine real-world evidence to bolster our evidence base further. A recently published study in BJGP Open aims to do this.

The study, conducted in New Zealand, evaluates the effect of cannabidiol (CBD) oil on quality of life, but importantly also sought to evaluate the incidence of side effects. CBD has been legal to prescribe in New Zealand following law changes in 2017.

Study design

Around 400 participants, diagnosed with a wide range of medical conditions including non-cancer chronic pain, mental health, neurological, and cancer symptoms, were assessed between December 2017 and December 2018. The patients had an average age of 51 and also had a relatively even proportion of biological sex. 253 patients went on to give feedback through a follow-up consultation.

In order to determine the effect of CBD on quality of life, participants completed an EQ-5D-5L questionnaire both prior to and following treatment. This two-part tool allows researchers to assess both overall feelings of health but also across 5 domains.

Results

Of the almost 400 patients prescribed CBD oil, 63% reported their satisfaction with treatment. 110 patients completed the EQ-5D-5L assessment providing insight into quality of life. A significant number of patients reported increased quality of life both on the whole, but also across the 5 domains including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The most drastic improvement was seen in those prescribed CBD for non-cancer pain symptoms, whereas no significant differences were found in neurological conditions. Patients with cancer symptoms experienced improvements in pain. Overall, 70% of the follow-up group reported some satisfaction with CBD treatment, and 30% reported no benefit.

An analysis of the side effects of CBD found that adverse events with CBD isolate therapy were low. Most common adverse effects were sedation (2%), vivid dreams (2%), emotional disturbance (2%) and disorientation (1.2%). Positive side effects such as improved sleep (12.3%) and appetite (2.8%) were also reported.

The authors of the study accepted that their study had a number of limitations. These included a large loss of participants to follow-up. Therefore, the results, though promising, may not be accurately indicative of the whole patient population.

Although this research has significant setbacks, it highlights the importance of collecting real-world evidence to improve the evidence base in medicinal cannabis as well as all medications. By implementing more comprehensive, prospective data collection such as that in the UK Medical Cannabis Registry we hope important information about this CBD, but also other forms of medicinal cannabis will be unlocked.