Background and Importance In clinical practice of chronic migraine treatment, changes between the different anti-CGRP monoclonal antibodies (mABs) on the market are made, but there are still no clinical trials to support the effectiveness of such a switch.

Aim and Objectives To determine the characteristics of the switches made between mABs (fremanezumab, galcanezumab and erenumab) in our hospital, and to evaluate the effectiveness of these changes.

Material and Methods Descriptive observational and retrospective study in a second-level hospital in which patients diagnosed with refractory chronic migraine from June 2020 to September 2023 and who had been on treatment with the three drugs, were included. Inclusion criteria: patients aged >18years, on treatment for at least 3 months with fremanezumab (225 mg/month), galcanezumab (120 mg/month (initial 240 mg) and erenumab (140 mg/month).

Demographic variables (sex, age), efficacy variables: monthly days with headache of at least moderate intensity (HMD) at 0, 3 and 6 months, type of drug used and timing, duration of treatment (DT (months)), and use of concomitant prophylaxis (CP) were collected. Changes with respect to baseline HMD were analysed, establishing as effective a change greater than 30% and 50%.

Results Eighteen patients were included, 71% female (N=13) and a median age of 44.6 (RIQ: 42.6–58.4) years. Patients had a mean and standard deviation (SD) 20.6 (SD 7.8) days of baseline headache. A total of 55 treatments were reviewed: 81% (N=42) received PC together with AcM. The median DT with fremanezumab, galcanezumab and erenumab was 6.7, 10.1 and 7 (SD 4.5, 7 and 5) months respectively. In terms of efficacy, two and three patients (11%/16%) respectively achieved at least a 50% and 30% reduction in headache days at the first change, and none at a second change of treatment, both at 3 and 6 months of treatment (all were on fremanezumab).

Conclusion and Relevance Following the active treatment protocols for chronic migraine with mABs in our centre at any given time, our patient sample shows that only a maximum of 16% of patients could be rescued, taking a 30% decrease in the number of headache days per month as efficacy.

Conflict of Interest No conflict of interest.