Systematic literature review and Bayesian network meta-analysis of episodic cluster headache drugs

The drugs used in Europe to treat episodic cluster headache (eCH) are mainly verapamil and lithium carbonate, even though topiramate and pizotifen can be used. Galcanezumab, a humanized monoclonal antibody was approved by FDA recently for prophylaxis treatment of eCH. In order to evaluate the efficacy of galcanezumab compared to the drugs used for the preventive treatment of eCH, a systematic literature review (SLR) and network meta-analysis (NMA) of only randomized controlled trials (RCTs) was performed.

A literature search in MEDLINE, Embase and Cochrane Library including RCTs and observational studies was conducted. The primary outcomes for the NMA included the main change from baseline in reducing ECH attacks while the percentage of responders was used to pairwise comparisons of the observational studies. The NMA was conducted using a fixed-effect model and a random-effects model with deviance information criterion (DIC) reported for both models. The surface under the cumulative ranking (SUCRA) was shown only for the model with the lower DIC.

Three RCTs and six observational studies were included in the SLR. The Bayesian NMA was performed on the two RCTs included in the SLR, specifically galcanezumab and verapamil studies. SUCRA indicated that galcanezumab had the highest probability of being the most effective treatment (probability = 66.33%) compared to verapamil (probability = 31.58%) and placebo (probability = 2.09%). Galcanezumab was also the treatment with the highest overall probability to be the second most effective (probability = 88.79%).

The results suggest that galcanezumab is more effective compared to verapamil as a prophylaxis treatment for reducing eCH attacks in adults. Further, head-to-head RCTs of galcanezumab vs. treatments using in clinical practice are needed to better assess its comparative efficacy and benefit-risk profile.