Study design and population
headache
This study was conducted as part of the All participants started with a 4-week baseline-assessment period, followed by a 12-week withdrawal period, consisting of instruction to withdraw abruptly from all acute headache medications and caffeine (‘advice-only’). Prophylactic treatment was tapered off and rescue medication was not allowed. In addition to initiation of withdrawal treatment, immediately prior to withdrawal, botulinum toxin A (BTA) or placebo injections were administered in a 1:1 randomised, double-blind manner [The study was performed in accordance with the declaration of Helsinki Ethical Principles and Good Clinical Practices and was approved by the local and national ethics committees.