Date of Award


Degree Type

Selective Evidence-Based Medicine Review

Degree Name

Master of Science in Health Sciences - Physician Assistant


Physician Assistant Studies


Objective: The objective of this selective EBM review is to determine whether or not onabotulinumtoxin-A decreases the frequency of headaches in adults with chronic migraines.

Study design: A review of two randomized controlled trials and one observational cohort that were published in peer-reviewed journals between 2010-2016.

Data sources: The study reviews were searched through PubMed and were selected based on types of studies, years they were published, relevance to the clinical question, and outcomes that were patient oriented.

Outcomes measured: Patient recorded headache diaries and telephone diaries were used to record the frequency of headaches. Any headache lasting >4 hours were recorded as headache days in the Diener et al study, while no headache at all was recorded as headache free-day in the Mathew et al. study.6,7

Results: In the study conducted by Vikelis et al., results showed a decrease in the frequency of headaches with a p-value <.001.8 In the Mathew et al. study, the results show that decrease of 50% or more was greater in the onabotulinumtoxin-A group compared to placebo; p-value <.027.6 The second study, conducted by Diener et al., showed that patients treated with onabotulinumtoxin-A had a significant change from headache day baseline compared to placebo (p<.001)7

Conclusion: Based off of the results from the studies, it is clear that onabotulinumtoxin-A decreases the frequency of headaches. All three studies show significant data that support the use of onabotulinumtoxin-A in decreasing frequency of chronic migraines. Studies used mean change from baseline and decrease of headache free days out of the month to measure their outcome.