Long-term study of the efficacy and safety of OnabotulinumtoxinA for the prevention of chronic migraine: COMPEL study

BACKGROUND: OnabotulinumtoxinA is approved for the prevention of headache in those with chronic migraine (CM); however, more clinical data on the risk-benefit profile for treatment beyond one year is desirable. METHODS: The Chronic Migraine OnabotulinuMtoxinA Prolonged Efficacy open Label (COMPEL) Study (ClinicalTrials.gov, NCT01516892) is an international, multicenter, open-label long-term prospective study. Adults with CM received 155 U of onabotulinumtoxinA (31 sites in a fixed-site, fixed-dose paradigm across 7 head/neck muscles) every 12 weeks (±7 days) for 9 treatment cycles (108 weeks). The primary outcome was headache day reductions at 108 weeks; secondary outcomes were headache day reductions at 60 weeks and change in the 6-item Headache Impact Test (HIT-6) score. Safety and tolerability were assessed by reviewing the frequency and nature of adverse events (AEs). AEs were determined at each visit through patient self-report, general non-directed and, for specific AEs, directed questioning, and physical examination. Subgroup analyses for safety and efficacy included, but were not limited to, patients with/without concomitant oral preventive treatment and acute medication overuse at baseline. RESULTS: Enrolled patients (N = 716) were 18–73 years old and most were female (n = 607, 84.8%). At baseline, patients reported an average 22.0 (SD = 4.8) headache days per month. 52.1% of patients (n = 373) completed the study. By 60 and 108 weeks, a significant reduction in headache days (− 9.2 days and − 10.7 days, respectively, P < 0.0001) was observed. Significant improvements (P < 0.0001) in HIT-6 scores (− 7.1 point change at week 108) were also demonstrated. 131 patients (18.3%) reported ≥1 treatment-emergent adverse events; most frequently reported was neck pain (n = 29, 4.1%). One patient reported a serious treatment-related adverse event (rash). No deaths were reported. CONCLUSIONS: The COMPEL Study provides additional clinical evidence for the consistency of the efficacy and for the long-term safety and tolerability of onabotulinumtoxinA for the prevention of headache in those with CM who have been treated with onabotulinumtoxinA every 12 weeks over 2 years (9 treatments) with the fixed-site, fixed-dose injection paradigm. TRIAL REGISTRATION: Trial registration number: NCT01516892. Name of registry: clinicaltrials.gov. Date of registration: January 20 2012. Date of enrollment of first patient: December 2011. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s10194-018-0840-8) contains supplementary material, which is available to authorized users.