1 Department of Internal Medicine/Nephrology, Ziekenhuis Groep Twente, Almelo, The Netherlands.
2 Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS) and Biomedical Signals and Systems (BSS), University of Twente, Enschede, The Netherlands.
3 Department of Internal Medicine, Division of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.