UK Medical Cannabis Registry: A Clinical Outcomes Analysis for Migraine

INTRODUCTION: Migraine is a primary headache disorder, which leads to diminished health-related quality of life (HRQoL). There is limited evidence assessing efficacy of cannabis-based medicinal products (CBMPs) for migraine. This study investigates the efficacy and safety of CBMPs to treat migraine headache using validated patient-reported outcome measures. METHODS: This case series utilizes data from the UK Medical Cannabis Registry. Primary outcomes included changes in Headache Impact Test 6 (HIT-6), Migraine Disability Assessment Test (MIDAS), Generalized Anxiety Disorder 7 (GAD-7), Single Item Sleep Quality Scale (SQS), and EuroQol 5-Dimensions 5-Levels (EQ-5D-5L) from baseline up to 24 months. Adverse events (AEs) and their severity were recorded. A p-value < 0.050 was statistically significant. RESULTS: Two hundred and three adult patients met inclusion criteria. Improvements at all intervals up to 24 months, relative to baseline, were observed in the HIT-6, GAD-7, SQS, and EQ-5D-5L (p < 0.010) and up to 12 months in the MIDAS (p < 0.050). Female sex (odds ratio [OR] 0.48, 95% confidence interval [CI] 0.23-0.98, p = 0.046) and a bottom quartile THC dose (OR 0.25, CI 0.06-0.93, p = 0.047) were negative predictors of MIDAS improvement. One in seven (n = 31; 15.27%) patients reported 249 AEs (n = 110, 44.18% mild; n = 79, 31.73% moderate; n = 57, 26.91% severe; n = 3, 1.20% life-threatening). DISCUSSION: CBMPs were associated with improvements in HRQoL measures up to 2 years, being relatively well tolerated. Higher THC doses were associated with a greater likelihood of improvement on migraine-specific measures, although wide confidence intervals warrant caution in interpreting results. CONCLUSION: Findings indicate utility of CBMPs for migraine, but randomized controlled trials are required to establish causation.