Long-term safety of OnabotulinumtoxinA treatment in chronic migraine patients: a five-year retrospective study

Abstract

Background: Real-world studies have shown the sustained therapeutic effect and favourable safety profile of OnabotulinumtoxinA (BoNTA) in the long term and up to 4years of treatment in chronic migraine (CM). This study aims to assess the safety profile and efficacy of BoNTA in CM after 5years of treatment in a real-life setting. Methods: We performed a retrospective chart review of patients with CM in relation to BoNTA treatment for more than 5years in 19 Spanish headache clinics. We excluded patients who discontinued treatment due to lack of efficacy or poor tolerability. Results: 489 patients were included [mean age 49, 82.8% women]. The mean age of onset of migraine was 21.8 years; patients had CM with a mean of 6.4 years (20.8% fulfilled the aura criteria). At baseline, patients reported a mean of 24.7 monthly headache days (MHDs) and 15.7 monthly migraine days (MMDs). In relation to effectiveness, the responder rate was 59.1% and the mean reduction in MMDs was 9.4days (15.7 to 6.3days; p < 0.001). The MHDs were also reduced by 14.9days (24.7 to 9.8days; p < 0.001). Regarding the side effects, 17.5% experienced neck pain, 17.3% headache, 8.5% eyelid ptosis, 7.5% temporal muscle atrophy and 3.2% trapezius muscle atrophy. Furthermore, after longer-term exposure exceeding 5years, there were no serious adverse events (AE) or treatment discontinuation because of safety or tolerability issues. Conclusion: Treatment with BoNTA led to sustained reductions in migraine frequency, even after long-term exposure exceeding 5years, with no evidence of new safety concerns.