OnabotulinumtoxinA in chronic migraine: is the response dose dependent?

BACKGROUND: OnabotulinumtoxinA has been widely used for control of chronic migraine. The aim of the current study was to evaluate the efficacy of different doses of the onabotulinumtoxinA therapy in patients with chronic migraine. METHODS: This is a retrospective paired comparison study on patients with chronic migraine who received at least 3 rounds of 150 units of onabotulinumtoxinA followed by at least 3 rounds of 200 units of onabotulinumtoxinA. The data from the patient-reported questionnaires about headache days, severe headache days and wearing off periods were reviewed. RESULTS: A total of 175 patients were included in this study. The headache days and severe headache days decreased from 13.62 ± 10.79 and 5.88 ± 6.73 to 11.02 ± 10.61and 4.01 ± 4.89 days, after increase in the onabotulinumtoxinA dose, respectively (P < 0.001 for both comparisons). The favorable effect of the 200 units compared to the 150 units of the onabotulinumtoxinA, was independent from the headache location and the duration of the onabotulinumtoxinA 150 units therapy; and persisted as patients continued to receive the higher dose of onabotulinumtoxinA. Increase in the onabotulinumtoxinA dose was also associated with a decreased wearing off period (P < 0.05). CONCLUSION: We found that increase in the onabotulinumtoxinA is associated with fewer headache and severe headache days. Future randomized clinical trials are needed to confirm the dose-dependent response to onabotulinumtoxinA.