Disclosure statement None of the authors of this manuscript have any conflicts of interest to disclose in relation to this manuscript. The authors confirm that the work described has not been published previously, that it is not under consideration for publication elsewhere, that its publication is approved by all authors, and that, if accepted, it will not be published elsewhere in the same form in English or in any other language, without the written consent of the copyright holder. All authors contributed in an important manner to the writing of the paper according to the guidelines of the International Committee of Medical Journal Editors (ICMJE). All authors have read and approved the manuscript, all authors take responsibility for the manuscript, and the submitting author has permission from all authors to submit the manuscript on their behalf. RV is a Senior Clinical Research Fellow of the Research Foundation – Flanders (FWO) and is supported by a Research Grant from the FWO (G060322N). SB is supported by the Paul Corris International Clinical Research Training Scholarship. SL is supported by the Wallenberg Foundation.