Obituary Prof. Dr Raymond (Ray) T. Krediet

On 15 November 2024, emeritus professor of kidney disease (University of Amsterdam) Ray Krediet passed away. Ray was an internationally, well-known nephrologist working as an involved clinician, appreciated teacher and, above all, an outstanding researcher in the Academic Medical Center (now Amsterdam UMC) in Amsterdam. Besides other nephrological fields of interest his main focus was dedicated to research into the peritoneal membrane.

Ray Krediet was trained in Amsterdam (University of Amsterdam, department of internal medicine BinnenGasthuis) and at Guy's Hospital in London. He was an internist in internal medicine in 1978. In 1979, he introduced a Continuous Ambulatory Peritoneal Dialysis (CAPD) program in the Netherlands, and in 1981, he became director of the Dialysis department of the Academic Medical Center in Amsterdam. In 1986, he wrote his PhD thesis: Peritoneal permeability in CAPD patients. From that time on, he was fascinated by the peritoneal membrane, and he focused his research on the exploration of the mechanisms behind peritoneal transport and the consequences of peritoneal dysfunction for patients. He was an important pioneer in this area. In 1999, he was appointed as a professor in Nephrology at the University of Amsterdam.

During this life, he taught numerous students in nephrology, trained internists as nephrologists and supervised students. He was secondary supervisor for nine, and primary supervisor for 20 colleagues, in dissertations mostly on the subject of peritoneal dialysis. In 1993, he introduced the PD-University in Amsterdam, a course to teach colleagues more about PD with the hope of increasing the number of PD patients.

Ray Krediet also held many organizational and/or scientific positions during his career, both at home and abroad. In the Netherlands, he was chairman of the Dialysis Group Netherlands (DGN: 1987–1989) and secretary of the Dutch Society for Nephrology (1991–1995). These organizations have since merged into the current Dutch Federation of Nephrology. Due to his scientific achievements and his passion for PD he has also been active in many international societies. In 1996, he was secretary of the ERA-EDTA congress in Amsterdam, and Council member of the ERA-EDTA from 1997 to 1999. In 2002–2005, he was Chairman of the ERA-EDTA Best Practice Guidelines. From 2003 to 2009, he was president of the Nephrology section of European Medical Specialists. In 2004, he was president of the joint congress if the International Society for PD (ISPD) and EuroPD in Amsterdam. From 2004 to 2006, he was president of the ISPD.

He initiated and stimulated scientific research in the field of PD and regularly chaired sessions in this field at international conferences. He wrote over 500 papers, collaborated and/or was editor of various manuals and journals. He was able to obtain more than 30 grants for his research. In addition, he was an initiator of NECOSAD, a national study into the quality of dialysis treatments in more than 2000 Dutch dialysis patients that started in 1997. Most patients could be followed until the end of their dialysis treatment. The results were described in numerous publications and are still referred to in international journals.

Ray will be remembered as an important “founding father” of CAPD putting this dialysis modality on the map as a good, safe and simple home dialysis treatment. Together with his colleagues, he developed CAPD into an important and productive line of research within the nephrology department. His research into the pathophysiology of peritoneal transport and the effect of various osmotic agents improved the results of PD.

In 2010, Ray retired, although he continued working. He remained active in the field of PD, supervised PhD students, gave lectures all over the world, and performed work for international journals, advisory committees, etc. The undersigned, now retired themselves, were able to witness his remarkable career, first as a resident physician and PhD student, later as direct colleagues. Dialysis and nephrology have undergone enormous development during this period. We owe him a great deal of gratitude.

Ray Krediet was often accompanied by his wife Yvonne when attending conferences. Ray and Yvonne were a close couple. We wish Yvonne much strength in coping with this great loss.