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I’ve been asked this question twice in the last month, once by a 70 year old patient who has taken up smoking weed to control her neuropathic pain (let’s call her ‘Rachel’) and the other a young man (‘Clive’) who is smoking cannabis to help control his chronic anxiety. The simple answer, following the publication of this week’s NICE Guideline on Cannabis-based medicinal products NG144 , is an unsurprising ‘no’. Unless of course you happen to have MS with spasticity for which NICE have approved Sativex, or chemotherapy induced nausea and vomiting for which they have approved Nabilone.
For severe treatment resistant epilepsy NICE concluded that the ‘limited evidence’ did not warrant a practice recommendation for any cannabis-based product. However, they also did not make a recommendation against their use by specialists in severe cases of treatment resistant epilepsy pending further research. For the rare childhood epilepsy syndromes Lennox-Gestaut and Dravet, a separate technology appraisal on the licensed drug Epidiolex (a highly concentrated form of cannabidiol) is due to be published next month.
The new NICE guideline will be welcomed by many, especially the parents of children with severe epilepsy syndromes. High profile cases of these children drove the change in the law a year ago making it legal for medical cannabis to be prescribed by specialist doctors, and for children with these syndromes there is RCT evidence of efficacy for cannabidiol NEJM 2018.
However, the vast majority of our patients who want medical cannabis are like Rachel and Clive. They have disabling long term conditions which we treat with blunt tools often with disappointing results. These conditions generally need a holistic, non-drug, long-term approach for successful management, but one of the unintended consequences of the legalisation of medical cannabis has been an increase in hope and expectation for patients that it may be a solution to their problem. One that for many patients appears to be more attractive and ‘natural’ (Rachel tells me, with a wink in her eye, that her weed is one of her 5 a day) than the licensed and evidence-based ‘chemicals’ we often prescribe.
Living with chronic pain, anxiety or neurological disease is hard, a daily struggle, so this increase in hope is totally understandable. It has led to private clinics to feed the demand, and for patients like Rachel and Clive who cannot afford these clinics it appears to have legitimised illicit, uncontrolled use for medical purposes. We are witnessing a shift in thinking around cannabis since the law change, from recreational drug to bona fide medical treatment, which may encourage such use. Another unintended consequence.
So, what about Rachel and her hope for a treatment to control her chronic pain? Managing these expectations for GPs is hard, but NG144 is quite clear that cannabis based drugs should not be offered for chronic pain unless part of a clinical trial. A recent systematic review PAIN 2018 for chronic non-cancer pain found that cannabis and cannabinoids were just not very effective. To achieve a 30% reduction in pain compared to placebo, the NNT were 25 and there was no evidence they were better than placebo to produce a ≥ 50% reduction in pain. The numbers needed to harm were 6. Similarly last year for neuropathic pain a Cochrane systematic review 2018 found a lack of good evidence that any cannabis based product works for chronic neuropathic pain.
And Clive, who is smoking cannabis to help is symptoms of chronic anxiety? A systematic review of trials of cannabinoids for the treatment of long term mental health disorders has just published Lancet Neurology. The conclusion was that there was no evidence that medical cannabis improved the symptoms of depression, ADHD or PTSD and it was associated with an increase in adverse events. There was a small improvement in anxiety symptoms in some trials, but the quality of the evidence was described as ‘very low quality’.
A valid criticism of these systematic reviews is the ‘rubbish in, rubbish out argument’ as most of the studies are small, low quality and looking at a heterogenous range of products and trials. It is fair to say that we have a lack of evidence, rather than evidence of lack, at this stage. Furthermore, all these studies have been short term so concerns regarding dependence and long-term effects on cognition and mental health have not been addressed.
So, where does this leave us and our patients? GPs are expert at managing patient’s hopes and expectations, and also at working with patients within their own belief systems. Neither Rachel nor Clive will be surprised by the NICE guideline, nor will they be impressed by the recent systematic reviews. The fact it seems to help them is all the evidence they need. But these publications will help us to help our patients at least make informed choices pending further research. There is genuine hope that from this research evidence-based effective treatments may emerge, but the current ‘opioid crisis’ we are seeing in chronic non-cancer pain should make us exercise great caution before recommending any cannabis-based products ahead of a supportive evidence base.
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