A study based on the UK Medical Cannabis Registry has provided encouraging insights into the effect of medical cannabis on disease symptoms and patients’ quality of life.
For people living with fibromyalgia, chronic widespread pain, sleep disturbances, and other manifestations such as digestive and cognitive dysfunctions are common experiences. These consequences impact the ability to perform normal daily and professional activities and are associated with a higher incidence of psychiatric comorbidities and fatigue.
The fact that currently available effective therapeutic options are limited adds to this burden: clinical evidence supporting pharmacological treatments is scarce, and even non-pharmacological strategies, mainly based on psychological interventions, have shown limited efficacy so far.
Therefore, the development of different types of approaches is needed. In this context, based on the hypothesis that a deficiency in endocannabinoid system activity could play a role in the pathophysiology of fibromyalgia, cannabis-based medicinal products have become a growing area of research interest. Although high-quality evidence supporting their efficacy is still limited, some studies have highlighted their contribution to improving pain symptoms, even in fibromyalgia specifically, with a good safety profile.
Using data collected from the UK Medical Cannabis Registry, a group of UK researchers evaluated the effect of cannabis-based medicines on specific fibromyalgia symptoms, health-related quality of life, anxiety, and sleep.
Effect on Symptoms
The study included 306 patients who had received a prescription for cannabis-based medicines specifically for fibromyalgia and who had taken them for at least one month.
The average age was 45 years, and the sample predominantly consisted of women (215 patients, 70.3%), consistent with the higher prevalence of fibromyalgia among females.
At baseline, approximately 49% of participants (149 subjects) were current cannabis users, 13% (41 subjects) were former users, and 38% (116 subjects) had never used cannabis.
The most commonly used forms were oils (118 patients, 41%) or a combination of oils and dried flower (137 patients, 47%), with median daily doses of THC and CBD being 100 mg and 20 mg, respectively.
Patient-reported outcomes assessed included fibromyalgia symptom severity (measured by the Fibromyalgia Symptom Severity Scale), sleep quality (measured by the Single-Item Sleep Quality Scale, SQS), pain (assessed with the VAS-Pain scale), generalized anxiety disorder (measured using the General Anxiety Disorder Scale, GAD-7), and health-related quality of life (measured with the EQ-5D-5L questionnaire).
All parameters were evaluated at baseline and at 1, 3, 6, and 12 months after treatment initiation.
Data analysis revealed a statistically significant improvement in overall health-related quality of life scores at all timepoints compared to baseline.
Symptom severity, sleep quality, and pain measures showed improvements at 1, 3, and 6 months of follow-up.
For generalized anxiety disorder, significant improvements compared to baseline were observed at 1 and 3 months.
Patients who were current or former cannabis users responded better to treatment compared to cannabis-naïve subjects.
Researchers also evaluated opioid use reduction as a secondary outcome, noting a decrease in opioid prescriptions at 3 months and at the end of follow-up, although this reduction was assessed as not clinically significant.
Regarding safety, 979 adverse events were recorded among 72 patients (23.5%), with the most common being fatigue (75 subjects; 24.5%), dry mouth (69 subjects; 22.5%), reduced concentration (66 subjects; 21.5%), and lethargy (65 subjects; 21.2%).
Positive Indications for Further Study
“The study results suggest improvements in fibromyalgia-specific symptoms, sleep quality, anxiety, and health-related quality of life following treatment with cannabis-based medicines, which were also generally well tolerated despite a higher incidence of adverse events in this population compared to patients with other conditions included in the registry,” the researchers commented.
“This analysis may provide important insights for clinical practice and help in designing the necessary randomized controlled trials.”
Reference
¹ Wang C, Erridge S, Holvey C, et al. Assessment of clinical outcomes in patients with fibromyalgia: analysis from the UK Medical Cannabis Registry. Brain Behav. 2023 Jul;13(7):e3072.
