Footnotes

• Contributors Study concept and design: PMB, AJL, SOS, AD and TTW. Gathering of data: PMB, TG, SOS and AD. Analysis and interpretation of data: PMB, TG, AJL, SOS, AD and TTW. Drafting of the manuscript: PMB. Critical revision of the manuscript: TG, AJL, SOS, AD and TTW.

• Competing interests PMB received support to attend academic meetings from Britannia Pharmaceuticals and the Movement Disorders Society and has received a grant from Britannia Pharmaceuticals, also supported by a grant from the Brazilian National Council for Scientific and Technologic Development (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico). AJL is funded by the Reta Lila Weston Institute of Neurological Studies, University College London, Institute of Neurology and reports consultancies for Britannia Pharmaceuticals and BIAL Portela. He also reports grants and/or research support: from the Frances and Renee Hock Fund, and honoraria from Britannia, Profile Pharma, UCB, Roche, Lundbeck, Teva, BIAL, Nordiclnfu Care, NeuroDerm. SOS has received support to attend academic meetings and honorarium from Teva, Lundbeck pharmaceuticals, Eisai, UCB Pharma, AbbVie Pharma. TTW has received support to attend academic meetings from Britannia Pharmaceuticals.

• Ethics approval Each project received approval from the local research ethics committee.

• Provenance and peer review Not commissioned; externally peer reviewed.