Medical cannabis: bridging the evidence gap

19-year old Lucy Stafford has spent half of her life taking strong opioids, including fentanyl, to control severe pain caused by the hereditary connective tissue disorder Ehlers-Danlos syndrome. She has been addicted to tramadol and endured numerous surgeries. According to Stafford—whose story was reported in The Guardian on Nov 3—she had no ambitions. No life. Then she was prescribed medical cannabis and, for the first time since she was 10 years old, her pain became manageable.

Medical cannabis is legal in roughly 30 countries worldwide. But Stafford is one of only around 100 people in the UK who have been prescribed medical cannabis, despite a change in UK law in 2018 that allows the drug to be prescribed under certain circumstances. And, as of November, 2019, the possibility of obtaining cannabis-based products for the management of chronic pain will be even more remote, at least in the UK.

On Nov 11, the UK’s National Institute for Health and Care Excellence (NICE) issued new recommendations for the two cannabis-related medicinal products for patients with multiple sclerosis and epilepsy. But the guidance explicitly recommends against prescribing cannabis-related products for chronic pain, citing high cost and inadequate evidence. The prohibitive recommendation includes cannabidiol (CBD; one of two main components of cannabis), Δ-9-tetrahydrocannabinol (THC; the psychoactive component), and synthetic forms of THC (dronabinol and nabilone). Stafford should be able to continue her use because the NICE guidance includes a grandfather clause for adults who started taking cannabis-based products before the new guidance was released.

Chronic pain affects an estimated one in five adults worldwide, with osteoarthritis and rheumatoid arthritis ranking among the top causes. And despite the paucity of scientific evidence regarding the efficacy of cannabis-based products for chronic pain and other conditions, their popularity is undeniable. One US survey found that 37% of surveyed people with rheumatic or musculoskeletal disorders were using medical marijuana (which is legal in 33 US states), according to findings presented at the American College of Rheumatology annual meeting (Atlanta, GA, USA). And a survey by the US-based charity Arthritis Foundation found that nearly 80% of respondents with arthritis were currently using CBD, had tried it in the past, or were considering it as a pain-relief option to manage symptoms of arthritis. CBD (with varying limits on THC content) is legal in all but three US states.

On the backdrop of this popularity, Arthritis Foundation has teamed up with rheumatologists and chronic pain specialists to establish initial guidelines for use of CBD by patients with arthritis. Top among these guidelines is a strong recommendation to discuss potential use of CBD with a physician, and a recommendation to purchase CBD from a reliable source (although they offer no suggestions on how to identify such sources). The guidelines also stress the lack of rigorous clinical evidence around CBD and the importance of not taking CBD in place of disease modifying antirheumatic drugs that help to prevent permanent joint damage.

Despite the more prohibitive environment, efforts are underway in the UK to fill the evidence gap around cannabis-related products. On Nov 7, an initiative called Project Twenty21 was launched by Drug Science—an independent scientific body founded by David Nutt, the former UK chair of the Advisory Council on the Misuse of Drugs—in conjunction with the United Patients Alliance. The project, which is backed by the Royal College of Psychiatrists, aims to enrol 20 000 patients taking medical cannabis by 2021, and it will assess the efficacy, safety, and patient-reported outcomes in an effort to “create the largest body of evidence on medical cannabis in Europe”.

Data from Project Twenty21 and other research initiatives will be invaluable for informing the appropriate indications for and use of CBD and other cannabis-related products, but more needs to be done. In the absence of sufficient guidance and regulation, many patients are driven to the illicit market as a source of cannabis-related products, with the risk of incurring more harm than good. As such, regulation of the global cannabis market—which was valued at approximately US$10 billion in 2018 and is forecast to reach nearly $40 billion by 2023—is urgently needed.

Legalities and evidence-based recommendations aside, the reality is that many patients with chronic pain seek out medicinal cannabis and cannabis-related products. As such, we applaud the Arthritis Foundation’s decision to put forth cautious guidelines for CBD use by patients with arthritis. For chronic pain sufferers in the UK, the wait for evidence continues.