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How real-world data can “bridge current evidence gaps” for medical cannabis use

Thousands of patients are using medical cannabis for conditions where there is ‘debatable’ clinical evidence



Researchers are calling for Real-World Evidence (RWE) databases to be developed

Thousands of patients are using medical cannabis for conditions where there is ‘debatable’ clinical evidence – a new paper highlights why regulators must take real-world data into account. 

A new study highlights the potential of cannabis to treat a broad range of conditions from chronic pain and intractable epilepsy, to mental illnesses such as anxiety, depression and schizophrenia. 

But despite thousands of patients using cannabis for these conditions, the data around many of them remains “controversial”.

Researchers are now calling for Real-World Evidence (RWE) databases to be developed in order to “bridge current evidence gaps” for the use of medical cannabis.

A team from Drug Science, the UK-based charity behind the paper, has published an in-depth summary of the latest developments in cannabis research, taking in account findings from global registry databases, major reviews and patient-reported outcomes.

It concludes that conditions which see the highest numbers of patients turning to medical cannabis, often have ‘debatable’ clinical evidence but good RWE.

Prescription registries reveal large numbers of patients are using cannabis to treat their arthritis, sleep disturbances, depression and anxiety, despite the limited RCT evidence. 

The strongest, most conclusive data to support the efficacy of cannabis based medicines is in conditions with relatively small patient numbers, such as intractable epilepsy, multiple sclerosis (MS), cancer-related nausea, and appetite stimulation in wasting disorders. 

Other, less common conditions, including fibromyalgia, schizophrenia, migraine, glaucoma and Tourette’s syndrome were found to have “limited proof of concept RCT or observational data” to support the use of medical cannabis, which the authors say warrants more research. 

Dr Anne Katrin Schlag

Dr Anne Katrin Schlag, head of research at Drug Science

Dr Anne Katrin Schlag, head of research at Drug Science tells, Cannabis Health: “When you look at the RCT evidence base for some of these conditions, it is in some ways controversial – it’s not as strong as many scientists and doctors would like it to be.

“But there are thousands upon thousands of patients globally, who have been using medical cannabis successfully to treat these conditions, which is really building a pattern of evidence.

She continues: “There are many conditions, which have quite a low strength of RCT evidence and also have low numbers of patients, but that evidence base is developing, which is very exciting.

“We argue that the evidence base should be widened to include these patient-reported outcomes.”

The nature of cannabis products, which are made up of many different combinations of compounds, makes conducting RCTs – which are widely viewed as the “gold-standard” of medical trials – challenging and time-consuming.

Research also shows that many patients with the conditions which could benefit most from cannabis treatments, also live with a number of co-morbidities, such as anxiety, depression and insomnia, which would make them ineligible for clinical trials.

“RCTs are the gold standard in medicine but in relation to medical cannabis that’s quite a challenge,” Dr Schlag continues.

“To complete RCTs for all the variations of potential cannabis based medicinal products and all the conditions cannabis is potentially useful for would take years, when many patients can benefit from the medicine now.”

Dr Schlag and her co-authors would like to see a systematic network of databases, with international guidelines for collecting RWE on cannabis medicines, which could help build this “pattern of data”.

“It’s really important that we pull these databases together in order to have a systematic collection of data, which could provide more support for medical cannabis,” she adds.

But even where the paper deems there to be a “high strength of data” for treatment with medical cannabis, for instance neuropathic pain, cancer-related pain and chronic pain, access remains limited for UK patients. 

The International Association for the Study of Pain does not endorse the general use of cannabinoids to treat pain, due to a “lack of evidence from high quality research” , and the National Institute for Health and Care Excellence (NICE) in the UK does not recommend doctors prescribe cannabis medicines for chronic pain.

A recent multi-criteria decision analysis by Drug Science found that medical cannabis improves patients’ quality of life more than any other treatment for chronic neuropathic pain, when compared to 12 of the most commonly prescribed prescription medications. 

The researchers say NICE and other regulators should take these findings into account.

“The evidence based globally has shown again and again that a large number of chronic pain patients are using medical cannabis to treat the condition, this is already out there, it’s already happening,” adds Dr Schlag.

“It’s time to have a discussion of how to incorporate these findings into decision-making.”


Sarah Sinclair is a respected cannabis journalist writing on subjects related to science, medicine, research, health and wellness. She is managing editor of Cannabis Health, the UK’s leading title covering medical cannabis and CBD, and sister titles, Cannabis Wealth and Psychedelic Health. Sarah has an NCTJ journalism qualification and an MA in Journalism from the University of Sunderland. Sarah has over six years experience working on newspapers, magazines and digital-first titles, the last two of which have been in the cannabis sector. She has also completed training through the Medical Cannabis Clinicians Society securing a certificate in Medical Cannabis Explained. She is a member of PLEA’s (Patient-Led Engagement for Access) advisory board, has hosted several webinars on cannabis and women's health and has moderated at industry events such as Cannabis Europa. Sarah Sinclair is the editor of Cannabis Health. Got a story? Email / Follow us on Twitter: @CannabisHNews / Instagram: @cannabishealthmag


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