Is There a Gender Difference in the Response to onabotulinumtoxinA in Chronic Migraine? Insights from a Real-Life European Multicenter Study on 2879 Patients

Introduction: Migraine is mostly a female disorder because of its lower prevalence in men. Less than 20% of patients included in the available studies on migraine treatments are men; hence, the evidence on migraine treatments might not apply to men. The aims of the present study were to provide reliable information on the effectiveness of onabotulinumtoxinA (BT-A) for chronic migraine in men and to compare clinical benefits between men and women. Methods: We performed a pooled patient-level gender-specific analysis of real-life data on BT-A for chronic migraine of patients followed-up to 9 months. We reported the 50% responder rates during each BT-A cycle, defined as percentage of reduction in monthly headache days (MHDs) compared to baseline, along with 75% and 30% responder rates. We also reported the mean decrease in MHDs and in days of acute medication use (DAMs) during each BT-A cycle as compared to baseline. We also evaluated the reasons for stopping the treatment within the third cycle. Results: We included an overall cohort of 2879 patients, 522 of whom (18.1%) were men. In men, 50% responder rates were 27.7% during the first BT-A cycle, 29.2% during the second, and 35.6% during the third cycle; in women, the corresponding rates were 26.6%, 33.5%, and 41.0%. In the overall cohort, responder rates did not differ between men and women during the first two cycles; during the third cycle, the distribution was different (P < 0.001) mostly because of higher rates of treatment stopping and non-responders in men. In the propensity score matched cohort, the trend was maintained but lost its statistical significance. Both men and women had a significant decrease in MHDs and in DAMs with BT-A treatment (P < 0.001). There were no gender differences in those changes with the only exception of MHD decrease which, during the third cycle, was lower in men than in women (7.4 vs 8.2 days, P = 0.016 in the overall cohort and 9.1 vs 12.5 days, P = 0.009 in the propensity score matched cohort). At the end of follow-up, 152 men and 485 women stopped BT-A treatment (29.1% vs 20.6%; P < 0.001). The relative proportion of patients stopping treatment because of inadequate response (less than 30% decrease in MHDs from baseline) was higher in men than in women (42.8% vs 39.6%), while the proportion of patients stopping because of adverse events was higher in women than in men (5.6% vs 0%; P = 0.031). Conclusions: Our pooled analysis suggests that the response to BT-A is significant in both men and women with a small gender difference in favor of women. Men tended to stop the treatment more frequently than women. We emphasize the need for more gender-specific data on migraine treatments from randomized controlled trials and observational studies.