OnabotulinumtoxinA 155 U in medication overuse headache: a two years prospective study.

The efficacy and safety of OnabotulinumtoxinA 155-195 U (BOTOX(®)) in adults with chronic migraine (CM) were demonstrated in both the Phase III Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) studies. However, data about its long-term efficacy and safety in clinical settings are scanty. Therefore, the objective of this study is to evaluate OnabotulinumtoxinA 155 U treatment in patients affected with CM and co-morbid medication overuse headache (MOH) over 2-year analysis. We prospectively evaluated 155 CM and MOH affected patients started on OnabotulinumtoxinA 155U (PREEMPT injection paradigm) between October 2010 and November 2011 and followed-up for 2 years. All patients failed to positively respond to previous multiple preventive therapies that were withdrawn before starting OnabotulinumtoxinA. Headache days, migraine days, acute pain medication intake days and Headache Impact Test (HIT)-6 score were used as efficacy measures, whereas safety was evaluated with side effects occurrence during the treatment phase. Baseline data were collected from patients headache diary referred to the previous month, and patients were evaluated every 3 months at the time of each injection. OnabotulinumtoxinA 155U significantly reduced the number of headache and migraine days (p < 0.001), acute pain medication intake days (p < 0.001) and HIT-6 score (p < 0.001) when compared with the baseline data. The reduction was significant after the first injection (p < 0.001), and gradually increased during the 2 years of treatment. Treatment related adverse events were transient and mild-moderate (e.g. headache, injection-site pain, eyelid ptosis, musculoskeletal weakness). This prospective 2-years analysis of efficacy and safety of long-term treatment with OnabotulinumtoxinA 155 U in patients affected with CM and MOH confirms the efficacy data from previous Randomized Clinical Trials for CM prophylaxis. Moreover, here we demonstrate that OnabotulinumtoxinA can be safely used for the long-term treatment of MOH comorbidity in CM.