Effectiveness and Safety of Chronic Migraine Preventive Treatments: A Systematic Literature Review

INTRODUCTION: Numerous medications are used for the preventive treatment of chronic migraine (CM), including oral treatments, onabotulinumtoxinA (onabotA; BOTOX), and calcitonin gene-related peptide (CGRP) monoclonal antibodies (mAbs). Despite substantial clinical trial evidence, less is published about the real-world experience of these treatments based on data routinely collected from a variety of sources. This systematic review assessed real-world evidence on the effectiveness and safety of preventive treatments for CM in adults. METHODS: A systematic search of MEDLINE, Embase, and the Cochrane library with back-referencing and supplementary searches retrieved data published between January 2010 and February 2020. Publications were screened, extracted, and quality assessed. Data were narratively synthesized. Search criteria included preventive medications for CM. Evidence was available for topiramate, onabotulinumtoxinA, CGRP mAbs (erenumab, galcanezumab, and fremanezumab). OnabotulinumtoxinA was most commonly assessed (55 studies), followed by erenumab (six studies), multiple CGRP mAbs (one study), and topiramate (one study). Long-term data (> 1 year) were available for onabotulinumtoxinA only, with erenumab reported up 6 months, topiramate up to 3 months, and multiple CGRP mAbs up to 12 months. RESULTS: Substantial data demonstrated that onabotulinumtoxinA reduces the number/frequency of headaches, concomitant acute medication use, and impact of headaches on well-being and daily activity. More limited evidence showed benefits for the same parameters with erenumab. Single studies suggested topiramate and multiple CGRP mAbs decrease the number/frequency of headaches and impact of headaches. To date, onabotulinumtoxinA is the only preventive treatment for CM that has long-term safety data in real-world settings reporting treatment-related adverse events of up to 3 years. CONCLUSION: While substantial real-world evidence supports the long-term effectiveness and safety of onabotulinumtoxinA, real-world data on other preventive treatments of CM are currently limited to short term effectiveness due to their more recent approvals.