Calcitonin gene-related peptide antagonists versus botulinum toxin A for the preventive treatment of chronic migraine protocol of a systematic review and network meta-analysis: A protocol for systematic review.

[BACKGROUND] Although calcitonin gene-related peptide antagonists and botulinum toxin A have been shown efficacy in preventing chronic migraine, there is no direct evidence for their comparative effectiveness. This review is to assess the comparative effectiveness and safety of calcitonin gene-related peptide antagonists and botulinum toxin A for chronic migraine using network meta-analysis.

[METHODS] OVID MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials will be searched for relevant randomized controlled trials from their inception to December 2019 without language restriction. We will include trials testing the effectiveness of calcitonin gene-related peptide antagonists or botulinum toxin A in patients with chronic migraine. The outcomes are mean change from baseline in the number of headache days, the mean change from baseline in the number of migraine days, the mean change from baseline in headache hours, responder rate, and adverse events rate. The methodological quality of the included randomized controlled trials will be evaluated using Cochrane Collaboration's risk of bias tool. Standardized mean difference will be used to synthesize continuous variables and risk ratio will be used to synthesize categorical variables. Pairwise and network meta-analysis will be performed using a frequentist method in netmeta package (R 3.5.0, www.r-project.org).

[RESULTS] Ethical approval and informed consent are not required for this systematic review. The results will be submitted to a peer-reviewed journal and conference abstracts for publication.

[CONCLUSION] The result of the review will systematically provide suggestions for clinicians, patients, and policy makers in the treatment of chronic migraine.PROSPERO registration number: CRD42018089201.