# Prescriber adherence to treatment guidelines for monoclonal antibodies against Calcitonin Gene-Related Peptide in migraine prophylaxis – a register-based cohort study

## TL;DR

This study examines how well doctors in Stockholm followed guidelines when prescribing migraine treatments called CGRP mAbs and finds that while guidelines were mostly followed, frequent drug switching led to lower treatment persistence.

## Contribution

The study provides empirical evidence on prescriber adherence and treatment persistence patterns during the national rollout of CGRP mAbs for migraine prophylaxis in Sweden.

## Key findings

- 97% of CGRP mAb prescriptions were issued by neurology or headache specialists, indicating adherence to prescriber qualification guidelines.
- Treatment persistence declined with each successive drug sequence, with a 12-month persistence rate of 58% in the first sequence and 46% in the third.
- Switching between CGRP mAbs was common, suggesting a need for clearer guidance to avoid unnecessary switches and improve treatment outcomes.

## Abstract

Calcitonin Gene-Related Peptide targeting monoclonal antibodies (CGRP mAbs) were introduced for migraine prophylaxis in Sweden through the National Joint Introduction process to ensure an equal, cost-effective, and appropriate national use. This study aimed to assess prescriber adherence to treatment guidelines and evaluate patient treatment persistence during the national introduction of CGRP mAbs.

In this register-based cohort study, we followed individuals with a migraine diagnosis or dispensation of migraine drugs within Stockholm County from July 2018 to June 2022. We evaluated the guidelines for CGRP mAb treatment (erenumab, fremanezumab, or galcanezumab) according to four categories: 1) patient eligibility, 2) prescriber qualifications, 3) treatment evaluation, and 4) monitoring/reporting. We used a Sankey diagram to illustrate treatment switching and discontinuation patterns and employed boxplots along with Kaplan-Meier estimates to assess the persistence to CGRP mAbs.

Among 93,263 eligible individuals, 2266 (2%) had at least one CGRP mAb dispensation. Most (90%) had a prior migraine diagnosis at the first CGRP mAb dispensation, and 66% had been dispensed at least two prior prophylactic drugs against migraine. In nearly all cases (97%), CGRP mAb prescriptions were issued by neurology or headache specialists. Switching between CGRP mAbs was common and treatment persistence declined across successive sequences. Overall median treatment duration was 5.8 months (interquartile range: 2.8–11.9 months) and was longer for erenumab than fremanezumab and galcanezumab in sequence 1, but not in sequence 2. Kaplan–Meier analysis revealed a 12-month persistence of 58% in sequence 1, 53% in sequence 2, and 46% in sequence 3. A higher persistence was observed for fremanezumab and galcanezumab compared with erenumab in sequence 1, while estimates were similar in sequence 2.

Prescribers within Stockholm County adhere well to CGRP mAb treatment guidelines, with dispensations largely supported by a sound medical rationale, indicating appropriate integration into clinical practice. Guidance on switching between CGRP mAbs is limited and our findings show frequent switching and reduced persistence across sequences. These insights can help clinicians avoid unnecessary switches and optimize migraine care and resource use.

The online version contains supplementary material available at 10.1186/s10194-026-02322-1.