BMJ Open, 10(2):029855. BMJ Publishing Group BMJ Open, Vol 10, Iss 2 (2020) Luedtke, K, Basener, A, Bedei, S, Castien, R, Chaibi, A, Falla, D, Fernández-De-Las-Peñas, C, Gustafsson, M, Hall, T, Jull, G, Kropp, P, Madsen, B K, Schaefer, B, Seng, E, Steen, C, Tuchin, P, Von Piekartz, H & Wollesen, B 2020, ' Outcome measures for assessing the effectiveness of non-pharmacological interventions in frequent episodic or chronic migraine : A Delphi study ', BMJ Open, vol. 10, no. 2, 029855 . https://doi.org/10.1136/bmjopen-2019-029855 Luedtke, K, Basener, A, Bedei, S, Castien, R, Chaibi, A, Falla, D, Fernández-De-Las-Peñas, C, Gustafsson, M, Hall, T, Jull, G, Kropp, P, Madsen, B K, Schaefer, B, Seng, E, Steen, C, Tuchin, P, Von Piekartz, H & Wollesen, B 2020, ' Outcome measures for assessing the effectiveness of non-pharmacological interventions in frequent episodic or chronic migraine: A Delphi study ', BMJ Open, vol. 10, no. 2, 029855 . https://doi.org/10.1136/bmjopen-2019-029855 BMJ Open