Competing interests: We have read and understood BMJ policy on declaration of interests and declare the following interests: TK is employed by the Charité - Universitätsmedizin Berlin, Germany. He has provided methodological expertise for CoLucid and Amgen, for which the Charité - Universitätsmedizin has received unrestricted funds. TK has received an honorarium from Novartis for a lecture on neuroepidemiology at a neuroscientific meeting and travel support from the International Headache Society to attend board meetings. TK has received honorariums for editorial services to the BMJ. RES has received consultant fees for participation in Eli Lilly clinical trial data monitoring committees unrelated to the topic of this editorial. JLR has no competing interests.