Declaration of interest
Prof. Dr. P.C.M. van de Kerkhof has consultancy services for: Celgene, Centocor, Allmirall, Amgen, Pfizer, Philips, Abbvie, Ely Lily, Galderma, Novartis, Jansen Cilag, Leo Pharma, Sandoz, Mitsibishu, Sandoz. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.