Treatment with onabotulinumtoxinA shows a significant reduction in multiple efficacy outcomes such as mean headache days for up to 108 weeks in chronic migraine condition with or without allodynia, according to study results published in 'The Journal of Headache and Pain'.

Chronic migraine (CM) can be effectively treated using onabotulinumtoxinA, but data investigating the effects of allodynia on preventive treatment responses is limited. Therefore, investigators conducted a subanalysis of COMPEL Study to determine the efficacy, safety and tolerability of onabotulinumtoxinA in CM people with and without allodynia.

A total of 9 treatment cycles comprising 715 patients were carried out. Patients were administered with onabotulinumtoxinA toxin 155 U every 12 weeks. The patients with allodynia were recognised using the Allodynia Symptom Checklist (scores ≥3). The assessment of reduction in monthly headache days from baseline for 105-108 weeks was considered as the primary outcome of the study. The assessments of moderate to severe headache days, health-related quality of life (Migraine-Specific Quality-of-Life Questionnaire [MSQ] v2) and disability (using the Migraine Disability Assessment [MIDAS] questionnaire) were considered under other outcomes. Safety and tolerability of treatment were evaluated by determining adverse events.

The results of the study indicated that OnabotulinumtoxinA was associated with a significant mean (SD) reduction in headache day frequency at week 108 corresponding to baseline in patients with (n = 289) and without (n = 426) allodynia that was significantly greater in patients without allodynia. There was a significant reduction in moderate to severe headache days at week 108 in patients with and without allodynia; although the decline was similar between groups. Improvement in MIDAS scores and MSQ subscale scores (Emotional Function, Role Function Preventive, Role Function Restrictive) were also observed at week 108, with a significant between-group difference in patients with and without allodynia. Safety and tolerability analysis suggested that OnabotulinumtoxinA was well tolerated in both subgroups.

"Allodynia group depicted a smaller treatment response for the decline in headache days, yet almost the same or greater treatment response for improvement in other measures. There were no new safety concerns, " the study authors noted.