Article History
Received: 21 May 2018
Accepted: 5 June 2018
First Online: 22 June 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: The study protocol (Eudractnr: 2008-006756-22) was approved by the ethical committees of Leuven university and the general hospital of the H Hart Tienen.