Predictors of botulinum toxin type A response in patients with migraine: a meta-analysis.

[BACKGROUND] Migraine is one of the most common neurological diseases, imposing a heavy burden on society. Botulinum toxin type A (BT-A) has been approved as a safe and effective preventive treatment; however, not all patients report effectiveness after BT-A treatment. Thus, identifying BT-A responders in advance is valuable for treatment. Several studies have shown that some characteristics of headache, like a shorter disease duration and the absence of medication overuse, are potential predictors of clinical response. This meta-analysis aims to identify predictors linked to BT-A in people with migraine.

[METHODS] PubMed, Web of Science, Embase and the Cochrane Library were searched for studies. All cohort studies reporting the factors of responders and non-responders to BT-A injection were selected.

[RESULTS] Eleven studies met the criteria for selection. Of the 18 factors identified, only six were reported in at least three studies. BT-A response was associated with disease duration (MD: -2.37, CI: [-4.03, -0.83],  = 0.0002). In sensitivity analysis, the outcome of headache days was also statistically significant (MD: 1.02, CI: [0.45, 1.59],  = 0.0004).

[CONCLUSION] The findings of this meta-analysis support disease duration and headache days as predictive factors of BT-A response in people with migraine. Injecting BT-A at an early stage might be beneficial for migraine patients. However, the predictors were based on a small number of studies; thus, more studies are needed to prove the outcome. Several other factors may be associated with the response to BT-A but reported in a few studies. Therefore, more studies are needed to evaluate additional predictors.