UK Medical Cannabis Registry: A Clinical Outcomes Analysis for Complex Regional Pain Syndrome.

BACKGROUND

Complex regional pain syndrome is characterized by severe, persistent pain. Emerging evidence suggests that cannabis-based medicinal products may represent a new therapeutic option. However, to date, no clinical studies have evaluated the effects of cannabis-based medicinal products in individuals with complex regional pain syndrome. The aim of this study is to assess changes in patient-reported outcome measures and the prevalence of adverse events associated with cannabis-based medicinal products prescribed for complex regional pain syndrome.

METHODS

This case series assessed changes in patient-reported outcome measures over 6 months in complex regional pain syndrome patients enrolled in the UK Medical Cannabis Registry. Adverse events were measured and graded using the Common Terminology Criteria for Adverse Events version 4.0.

RESULTS

A total of 64 patients were identified for inclusion. At baseline, pain severity measured by the Brief Pain Inventory Short Form was 6.69 ± 1.42. This improved at 1 (5.85 ± 1.73), 3 (5.91 ± 1.82), and 6 months (6.05 ± 1.72; p < 0.050). Participants also reported improvements in severity as measured by the Short Form-McGill Pain Questionnaire-2 and pain visual analogue scale at the same time points (p < 0.050). Participants also reported improvements in anxiety symptoms, sleep quality, and general health-related quality of life (p < 0.050), as measured by validated measures. Five patients (7.81%) reported 50 (78.13%) adverse events.

DISCUSSION

This study represents the outcomes in individuals with complex regional pain syndrome prescribed cannabis-based medicinal products. These suggest initiation of cannabis-based medicinal products is associated with improvements in patient-reported outcome measures. While these findings are consistent with the literature, they must be interpreted with caution, considering the limitations of this study.

CONCLUSION

Cannabis-based medicinal products were associated with improvements in pain severity and interference. Participants also reported improvements in important metrics of health-related quality of life. This supports further research through high-quality randomized controlled trials to ascertain the efficacy of cannabis-based medicinal products in improving complex regional pain syndrome symptoms.