Received: 20 October 2017
Accepted: 29 December 2017
First Online: 1 February 2018
Ethics approval and consent to participate
: The Institutional Review Board of the MUMC approved this study (December 2011, project number 114069).
: Not applicable
: HTC is consultant at Stago. The other authors state that they have no conflicts of interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.