Use of Medical Cannabis in Patients with Fibromyalgia to Relieve Pain and Depression

Medical Cannabis in Therapy for Patients with Fibromyalgia Syndrome

Medical cannabis is approved for several indications, including chronic intractable pain associated with cancer, degenerative musculoskeletal disorders, neuropathic pain, or pain from glaucoma. The following retrospective study was conducted in neighboring Germany, where medical cannabis has been prescribable since March 2017. The aim of the study was to evaluate the efficacy of THC within interdisciplinary multimodal pain therapy (IMST). In addition to its impact on pain, efficacy on several psychometric variables (depression, anxiety, quality of life, sleep disorders) was assessed.

Patient Population and Study Procedure

All patients over 18 years with fibromyalgia syndrome hospitalized in the pain treatment department in 2017-2018 with multimodal interdisciplinary treatment, who met at least 3 inclusion criteria (previous unsuccessful outpatient therapy, severe deterioration in quality of life with disruption of lifestyle or job performance, inadequate pharmacotherapy, psychosocial risk factors, or psychological comorbidity, relevant somatic comorbidity) were included in the study. Exclusion criteria were insufficient data (n = 25), THC treatment at hospital admission (n = 1), treatment termination due to adverse effects (n = 2), and premature pain therapy termination during hospitalization (n = 4).

At the start of hospitalization, patients were examined by an algologist, psychotherapist, and physiotherapist, and their treatment was individually tailored. The structured regimen, including both individual and group therapies (maximum 8 participants), included components such as education, physiotherapy, exercise, psychotherapy, art therapy, natural treatment procedures, pharmacotherapy, and others.

During the study period, patients were given dronabinol (the psychoactive stereoisomer of THC (–)-Δ9-trans-tetrahydrocannabinol) exclusively in capsule form or liquid form. Dronabinol therapy was initiated at a dose of 1.25 mg, escalating by 1.25–2.5 mg daily for capsules, and 2 drops (1.6 mg) increasing by 1–2 drops daily for liquid form. Dose escalation was delayed until adverse effects subsided before further increase. Dose escalation was stopped based on sufficient pain relief, intolerable side effects, or reaching the legally set maximum daily dose of 33 mg.

The hospitalization duration was either 7–13 days (average 9.2 days) or 14–20 days (average 16.7 days). Patients were divided into two groups (with THC and without THC), and parameters such as pain intensity, psychometric parameters, and analgesic consumption were assessed during IMST. Patients in the control group received treatment per recommendations for managing fibromyalgia pain. Each participant filled out a questionnaire before hospitalization and at its conclusion.

Results

Of the 120 patients with FMS, 51.7% (n = 62) were treated with THC. This group had significantly more patients in chronic stage 3 than the control group. Both groups had a similar average number of pain-related comorbidities (3.7 vs. 3.3), most commonly including back and spine pain, limb pain, neuropathic pain, and headache. Both groups also had frequent psychiatric diagnoses (1.6 vs. 1.4), most commonly depression, anxiety, post-traumatic stress disorder, personality disorder, somatoform disorder, or addiction.

Target Dose

THC dose titration took an average of 13.4 days, with an average daily THC dose of 14.8 mg (range 2.6–31.3 mg). During hospitalization, patients on THC showed significant improvement (p < 0.001) in pain intensity, depression, and quality of life parameters.

Pain

Pain intensity on a 10-point scale decreased from 6.04 to 4.24 in patients with THC, while the control group saw a smaller change (from 5.58 to 4.24; p = 0.001). Five out of seven other analgesic medications were reduced or discontinued in THC-treated patients.

Depression

Depressive symptoms, measured by the HADS-D score (0–21), significantly decreased from 11.61 to 9.56 in the THC group, compared to the control group (drop from 9.66 to 8.72), a statistically significant difference (p = 0.037).

Quality of Life

The QLIP score (0–43) significantly increased in the THC group from 9.81 to 19.31, showing much greater improvement than the control group (from 11.76 to 17.6; p = 0.004).

Conclusion

Patients with fibromyalgia treated with synthetic THC during IMST provided during hospitalization experienced significantly greater pain relief compared to those receiving standard therapy. THC-treated patients also showed greater improvements in depressive symptoms and quality of life. THC administration also led to a higher frequency of discontinuation or reduction in concurrent analgesic medication.

The results of this retrospective study suggest that medical cannabis can be considered a therapeutic alternative to other analgesics. Medical cannabis, available on the market in the form of capsules or extracts, hence represents a new modality for patients with intractable pain, including pain associated with fibromyalgia.

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