Continuous combined oral contraceptive use versus vitamin E in the treatment of menstrual migraine: rationale and protocol of a randomized controlled trial (WHAT!).

"Declarations Ethics approval and consent to participateThe study is performed in accordance with the declaration of Helsinki Ethical Principles and Good Clinical Practices and was approved by the local and national ethics committees (NL67994.058.19). Competing interestsThe authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: B.W.H. van der Arend, D.S. van Casteren, I.E. Verhagen, A. MaassenVanDenBrink and G.M. Terwindt report independent support from the Netherlands Organization for Health Research (849200007) and the Dutch Brain Foundation (HA2017.01.05). A. MaassenVanDenBrink reports consultancy or industry support from Novartis, Lillyand Teva, and Allergan/Abbvie and independent support from the Dutch Research Council (Vici grant) and the Dutch Heart Foundation. G.M. Terwindt reports consultancy or industry support from Novartis, Lilly and Teva, Allergan/Abbvie, and Lundbeck and independent support from the European Community, Dutch Heart Foundation, IRRF and Dioraphte. Competing interests The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: B.W.H. van der Arend, D.S. van Casteren, I.E. Verhagen, A. MaassenVanDenBrink and G.M. Terwindt report independent support from the Netherlands Organization for Health Research (849200007) and the Dutch Brain Foundation (HA2017.01.05). A. MaassenVanDenBrink reports consultancy or industry support from Novartis, Lillyand Teva, and Allergan/Abbvie and independent support from the Dutch Research Council (Vici grant) and the Dutch Heart Foundation. G.M. Terwindt reports consultancy or industry support from Novartis, Lilly and Teva, Allergan/Abbvie, and Lundbeck and independent support from the European Community, Dutch Heart Foundation, IRRF and Dioraphte."

"Funding This trial is supported by grants from the Netherlands Organization for Health Research (849200007) and the Dutch Brain Foundation (HA2017.01.05)."

"Trial registration Clinical trials.gov NCT04007874. Registered 28 June 2019."