Wearing Off Response to OnabotulinumtoxinA in Chronic Migraine: Analysis in a Series of 193 Patients

Objective: Long-term real-life studies have supported a cumulative effect of OnabotulinumtoxinA (OnabotA) for the prophylactic treatment of chronic migraine (CM) during consecutive cycles, and individual adaptations have been described to improve clinical response. Methods: This was a cohort longitudinal retrospective study of consecutive adult patients from the Headache Unit of the Hospital Clinico Universitario de Valladolid and the Hospital Universitario de La Princesa (Madrid) on OnabotA treatment for chronic migraine from May 2012 to December 2017. All patients were followed for 24 weeks. Full-length response to OnabotA was defined as ≥50% reduction in headache days for at least 12 weeks, and wearing off response was defined as a clinical response but with duration shorter than 10 weeks. We have analyzed the incidence and clinical predictors of this wearing off response. Results: A total of 193 patients were included, of whom 91 (47.1%) were considered full-length responders and 45 (23.3%) wearing off responders. No statistically significant clinical predictors (including demographic variables and baseline headache characteristics) of full-length response or wearing off response were detected in our study. An increase in dose during the second treatment cycle was attempted in 68.9% of the wearing off patients, achieving a longer duration of response of up to 12 weeks in 74.2%. Conclusions: Wearing off response to OnabotA during the first treatment cycle is not uncommon in patients with CM. Increasing the dose in subsequent cycles could improve clinical response, but further multicenter long-term studies are needed to establish predictors and solutions to this problem.