Competing interests
D Montani, X Jaïs, L Savale, M Humbert, G Simonneau and O Sitbon have been supported by Actelion, Bayer Schering, GlaxoSmithKline, Novartis, Pfizer, Inc., Lilly & Co., and United Therapeutics for consultancy services and as members of their scientific advisory boards. The other authors declare that they have no competing interests.