Objective: To examine whether cannabis use predicts medication overuse headache (MOH) in chronic migraine (CM) patients.
Methods: Electronic chart review was conducted by combining the terms “chronic migraine”, “medication overuse”, “cannabis”, “CBD”, “THC” for patients seen at our headache clinics from 2015 to 2019. Of 729 charts identified, 368 (150 using cannabis; 218 not using cannabis) met our inclusion criteria, i.e., adult CM patients with ≥ 1-year CM duration. The following variables were extracted from each patient’s chart: MOH diagnosis as dependent variable, and predictor variables as age, sex, migraine frequency, current CM duration, current cannabis use duration, overused acute migraine medications, current MOH duration, and types of cannabis products used. Logistic regression was employed to identify variables predicting MOH while controlling for remaining predictors. Agglomerative hierarchical clustering (AHC) was conducted to explore natural clusters using all predictor variables.
Results: There were 212 CM patients with MOH ( cases ) and 156 CM patients without MOH ( referents ). Current cannabis use statistically significantly predicted cases with MOH – odds ratio 6.0 (3.45, 10.43), p < 0.0001. Current cannabis use, opioid use, and MOH were significantly associated. AHC revealed two major natural clusters. Cluster I patients were younger with less migraine frequency, higher MOH burden, more current cannabis and opioid users than cluster II.
Conclusion: Cannabis use significantly contributes to the prevalence of MOH in CM. Bidirectional cannabis-opioid association was observed – use of one increased use of the other. Advising CM patients with MOH to reduce cannabis use may help treat MOH effectively.