Efficacy and Contextual (Placebo) Effects of CGRP Antibodies for Migraine: Systematic Review and Meta‐analysis

Raeburn B. Forbes*, Mark McCarron, Chris R. Cardwell

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

3 Citations (Scopus)

Abstract

Background: 

CGRP Antibodies are high-cost newly licensed migraine preventatives. 

Objective: 

To calculate the overall reduction in monthly migraine days and the proportion contextual effect (PCE) using meta-analysis. The PCE is the ratio between the reduction in Monthly Migraine Days in the placebo group and the reduction in Monthly Migraine Days in the CGRP-Ab group after 3 months of treatment.

Methods: 

Meta-analysis of randomized double-blind placebo-controlled trials of anti-CGRP antibodies in people with episodic migraine (EM) or chronic migraine (CM) in persons aged 18 or over. Non-randomized trials and trials in persons under 18 years excluded. Search of National Clinical Trials Register 2000-2019, MEDLINE to September 2019, Hand search of major headache conference abstract books 2012-2019. Two investigators used standard proforma to reach consensus. Trial quality assessed using Cochrane Collaboration risk of bias tool. PRISMA guidelines followed. 

Results: 

21 completed trials with 13367 participants (8075 EM, 5292 CM). Compared to placebo, pooled reduction in MMD was 1.50 days in 15 EM trials (95%CI 1.16, 1.84; I2 = 69%, Phetereogeneity <.001) and 2.24 days in 7 CM trials (95%CI 1.82, 2.65, I2 = 15%, Phetereogeneity =.320). In EM trials, pooled PCE was 0.66 (95%CI 0.59,0.75; I2 = 64%, Phetereogeneity =.001). In CM trials the PCE was.68 (95%CI 0.61, 0.75; I2 = 20%, Phetereogeneity =.280). Industry funded every study, but risk of bias was low. 

Conclusions: 

CGRPAbs are effective but sixty-six percent of the benefit is from contextual effects, including placebo effect. Contextual effects merit further scrutiny as a means of improving migraine headache.

Original languageEnglish
Pages (from-to)1542-1557
Number of pages16
JournalHeadache
Volume60
Issue number8
Early online date15 Jul 2020
DOIs
Publication statusPublished - 02 Sep 2020

Bibliographical note

Funding Information:
Hazel Neale, Craigavon Area Hospital Medical Library.

Publisher Copyright:
© 2020 American Headache Society

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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