As we find ourselves navigating the vast world of medical research, it is always invigorating to stumble upon promising explorations that could potentially shape the future of therapeutic options. Today, we delve into one such exploration: the potential use of medical cannabis in the treatment of fibromyalgia. A recent study titled “Assessment of clinical outcomes in patients with fibromyalgia: Analysis from the UK Medical Cannabis Registry”, led by researcher Claire Wang, takes center stage in our discussion.
Firstly, let’s understand the condition at hand – Fibromyalgia. This is a syndrome that, much like a uninvited guest, brings along a spectrum of symptoms including chronic musculoskeletal pain, sleep disturbances, cognitive dysfunction often referred to as “fibro fog”, and digestive issues. Affecting approximately 4% of American and European populations, fibromyalgia can significantly impair one’s ability to perform daily tasks, and often coexists with psychiatric conditions.
Conventional treatment for fibromyalgia primarily revolves around a biopsychosocial model which incorporates non-pharmacological approaches such as cognitive-behavioral therapy, psychotherapy, and exercise-based methods. Unfortunately, the effectiveness of pharmacological treatments remains a matter of debate, often leaving patients wrestling with persistent symptoms. This underlines the urgency for the exploration of new therapeutic options capable of addressing the myriad of symptoms that accompany fibromyalgia.
Enter medicinal cannabis, the newfound beacon of hope. The cannabis plant is a treasure trove of over 140 pharmacologically active cannabinoids, compounds that interact with the endocannabinoid system — an influential player in the central nervous system and the inflammatory response. Of these, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), are the most abundant and have shown promising potential benefits.
THC reduces nociceptive signal transmission and induces psychoactive effects as a CB1 receptor partial agonist, while CBD inhibits the hydrolysis of endocannabinoid anandamide, potentiating the effects of TRPV1 desensitization and reducing the sensation of noxious stimuli. CBD also acts as an agonist of selective serotonin 1A (5HT1A) receptors, producing anxiolytic effects.
Despite the potential benefits, high-quality evidence on the efficacy of cannabis-based medicinal products (CBMPs) for treating fibromyalgia remains elusive. Wang’s study, however, offers a ray of hope as it aims to evaluate the effects of CBMP treatment on fibromyalgia-specific symptoms, health-related quality of life, anxiety, sleep, as well as changes in opioid consumption and potential adverse events.
A Closer Look at the Study
In this study, the researchers analysed data from 306 fibromyalgia patients registered on the UK Medical Cannabis Registry (UKMCR) who met specific criteria. The participants exhibited a range of smoking, alcohol consumption, and cannabis use habits.
For treatment, CBMPs were administered in various forms, with the majority receiving a combination of oral/sublingual oil preparations and vaporised dry plant preparations. The most common oils were Adven® 20 THC and Adven® 50 CBD, while the most common dried flower preparation was Adven® EMT1 19% THC.
The findings were intriguing. Patients exhibited an overall improvement in health-related quality of life and scores indicating symptom severity, sleep quality, pain intensity, and patient-perceived improvement increased over the course of 12 months compared to the baseline. Notably, among patients with a history of cannabis consumption, statistically significant improvements were also reported.
Surprising Benefits for Cannabis Users
Perhaps one of the most striking observations to emerge from the study was the differential impact of Cannabis-Based Medicinal Products (CBMP) on patients with a history of cannabis consumption. In this subset of the study participants, significant improvements were noted in key metrics like fibromyalgia symptom severity, sleep quality score (SQS), pain intensity on a visual analog scale (VAS-Pain), and overall health-related quality of life, as indicated by the EQ-5D-5L index value. These improvements were consistent across all follow-up periods – 1, 3, and 6 months – compared to the baseline.
These results not only highlight the efficacy of CBMPs in treating fibromyalgia symptoms but also suggest that those with prior cannabis use might particularly benefit from CBMP treatment. Interestingly, the patient-perceived improvement, as measured by the Patient Global Impression of Change (PGIC) scores, also showed an upward trend over time in this group.
There are several plausible reasons for these findings. Patients with a history of cannabis use might already have some tolerance to cannabis, leading to fewer side effects and better adherence to CBMP treatment. Additionally, their pre-existing familiarity with the effects of cannabis might also contribute to more positive expectations and improved outcomes. However, these are hypotheses, and the study does not directly elucidate the reasons behind the superior outcomes among prior cannabis users.
While there were adverse events reported by 23.5% of participants, they primarily fell into categories of mild to moderate severity, including fatigue, dry mouth, and concentration impairment, among others. There were no life-threatening or disabling adverse events reported. It is also interesting to note that these events varied across groups of cannabis naïve, current user, and ex-user groups, as well as different administration methods.
Discussing the Implications
The findings of Wang’s study shed some much-needed light on the potential therapeutic effects of CBMP treatment in fibromyalgia patients. Notably, the study suggests a significant improvement in fibromyalgia-specific symptoms, pain, sleep, anxiety, and overall health-related quality of life following the initiation of CBMP treatment. Furthermore, the study observes a reduction in opioid consumption, which could potentially steer the conversation around alternatives to opioids for chronic pain management.
The reduction in Fibromyalgia Symptom Severity scores in this study echoes previous research, reinforcing the prospect of CBMP use in alleviating fibromyalgia symptoms. Moreover, improvements in the Self-Care domain of EQ-5D-5L were also reported, a finding that differs from earlier studies involving chronic pain cohorts. The reported decrease in pain and improvement in sleep quality supports previous research on the positive effects of CBMP on pain management and sleep quality in fibromyalgia patients.
The study also uncovered improvements in anxiety and depression scores, further supporting the possibility that CBMPs could address multiple aspects of the impacts of fibromyalgia. A significant reduction in opioid consumption following CBMP treatment may hint at a safer pain management approach with lower risks of serious adverse events and dependency.
Despite these promising findings, it’s important to acknowledge that the study reported a relatively high incidence of adverse events compared to other conditions within the UKMCR. This could be due to fibromyalgia patients’ heightened sensitivity to medication or the higher prevalence of the condition among women, who are generally more likely to report adverse events.
Addressing the Limitations
As with any research, it’s crucial to recognise the limitations of this study. The observational nature of the study means that causality cannot be definitively established and biases such as regression to the mean and attrition cannot be ruled out. The reliance on self-reported data may also introduce over-reporting, recall bias, and confirmation bias. Furthermore, the study’s dependence on private prescriptions for unlicensed CBMPs may not fully represent the wider U.K. fibromyalgia population. Multiple analyses also heighten the risk of a Type I error, and some initially significant findings became nonsignificant after a Bonferroni correction.
Concluding Thoughts
Despite its limitations, the study by Wang et al., represents a valuable contribution to the understanding of CBMPs’ potential in treating fibromyalgia. It offers insights into the possible improvements in fibromyalgia-related symptoms, sleep quality, anxiety, and overall quality of life following CBMP treatment. It’s intriguing to note the amplified benefits among patients with prior cannabis use. However, as is the case with all observational studies, causality cannot be definitively established, and the findings need to be substantiated with randomised controlled trials. While the evidence on CBMPs in fibromyalgia treatment remains a work in progress, the findings of this study illuminate a promising pathway towards more effective management of this debilitating condition.
Reference
Wang C, Erridge S, Holvey C, Coomber R, Usmani A, Sajad M, Guru R, Holden W, Rucker JJ, Platt MW, Sodergren MH. Assessment of clinical outcomes in patients with fibromyalgia: Analysis from the UK Medical Cannabis Registry. Brain Behav. 2023 May 18:e3072. doi: 10.1002/brb3.3072. Epub ahead of print. PMID: 37199833.