Long-term adherence, safety, and efficacy of repeated onabotulinumtoxinA over five years in chronic migraine prophylaxis

Background OnabotulinumtoxinA (BoNTA) demonstrated a positive benefit-risk in chronic migraine (CM) patients in PREEMPT I and II phase III trials and many subsequent real-world studies. We herein aimed at evaluating the adherence to repeated BoNTA over a period of five years, while secondary objectives included the assessment of its long-term safety/efficacy and patients' satisfaction to treatment. Methods We studied 56 CM patients who had successfully received consequent cycles of BoNTA over five years. Adherence was calculated as the percentage of patients actively choosing to follow with repeated BoNTA treatment, as instructed. Safety and efficacy data were collected throughout the study period. The overall patients' belief in and satisfaction by the efficacy of treatment was assessed at last follow-up, using the self-report 7-point measure patient global impression of change (PGIC). Results A total of 36 (64.3%) out of 56 patients remained adherent to BoNTA over five years. Long-term BoNTA exposure was safe and well-tolerated, without severe side-effects justifying treatment discontinuation. The mean monthly headache days and associated clinical efficacy outcomes remained consistent and quite low at last follow-up with evidence of continuous improvements in headache monthly frequency between year three and over five years of therapy. All patients who were able to maintain treatment over five years (n = 36), remained very satisfied and scored at least 5 in PGIC. Conclusion Considerably high adherence, considerable satisfaction and sustained safety/efficacy were observed in patients followed up for five years, supporting a favorable benefit/risk profile for consistently delivering long-term BoNTA in CM.