In this study the charts of 336 consecutive migraine patients treated with CGRP-antagonists at the Cleveland Clinic during roughly the last half of calendar year 2018 were reviewed. They had to have had at least one 3 month follow-up. These patients were assessed as to how much improvement they had over time and assigned to 4 categories regarding that: marginal/no improvement, 50%, 75% and 100%. How the response was graded was not clear, presumably by the reduction in headache days (i.e. if someone reported half as many headache days than previously, they would earn a 50% score). Since HIT 6 scores were used this might have been a metric as well. Adverse effects were also assessed in these patients. It was not made clear which patients or how many were using which of the 3 available CGRP monoclonal antibodies available at the time.
52 of 114 patients with episodic migraine and 105 of the 222 patients with chronic migriane had 50% improvement or better. No demographic factors such as age, sex, mass, or marital status were predictive of improvement of lack of improvement. No historical features such as numbers of failed medication trials were predictive either. In terms of adverse effects, constipation was reported more than was predicted by previous drug trial data.
We should probably interpret these data with caution. It is possible that the requirement for follow up led to undercounting patients who derived little benefit from the treatment. Placebo effect was probably important given that these were brand-new drugs supported by lots of enthusiasm. The retrospective chart review design does not allow assessment of this. In drawing conclusions from this study it might be important to know the proportions of erenumab, fremanezumab and galcanezumab – presumably mostly erenubab since it came first, though it is not yet clear what the differences in AEs and benefits are regarding these three monoclonal antibodies.
Finally, as the authors noted, more time will be needed to assess long-term adverse effects, and whether benefits will be sustained. But real world experience is always of value and this review does tend to build confidence in this new class of anti migraine prophylactics.