Interview with Prof P.E. de Jong

Prof P.E. de Jong Dept. of Medicine, Div. of Nephrology University Hospital Groningen Groningen, The Netherlands

Prof Zoccali: You have a strong interest in Preventive Nephrology. This area has received only scarce attention until a few years ago, but now there is growing interest in it. Why is it so?

Prof de Jong: This is indeed an intriguing phenomenon. In my opinion, prevention has in fact been put on the political agenda more by the developing countries than by the industrialised Western world. I feel we, in the developed world, have for too long a time had all the opportunities to start hemodialysis and transplantation whenever we felt it needed to be done. In the developing countries however, the facilities are not that widespread, that one is unable to offer renal replacement programs to everyone who should in fact be treated. Those countries realised earlier that the only way to keep the patient alive is to detect him in an early phase that still allows starting renoprotective regimens.

In that respect, we must realise that in the sixties to eighties we were aiming at tertiary prevention, that is, to prevent the complications (mostly cardiovascular) of patients in hemodialysis and transplantation. In the eighties the attention shifted towards secondary prevention, that is, to prevent the patient with a given renal disease towards progression to end stage renal disease (ESRD). Only recently we shifted attention also to primary prevention, that is, to prevent the renal disease occurring at all, or more frequently, to prevent the renal damage that may manifest itself due to various atherosclerotic, be it hemodynamic or metabolic, risk factors.

Prof Zoccali: Nephrology as a medical speciality has a strong hospital base. How do you think that renal physicians may be convinced to go out of hospitals to found Community Nephrology?

Prof de Jong: We will have to do so, when we realise that at present more than half of the patients presenting with ESRD have this far advanced renal failure not related to a primary renal disease, but due to either renal vascular disease (mostly generalised atherosclerosis), type 2 diabetes or unknown causes. As these patients mostly do not experience classical renal symptoms (edema, hematuria, flank pain, etc) in general they will not be seen at all by the nephrologist, unless they have symptomatic ESRD. At that time however, the nephrologist mostly cannot do more than start dialysis and (again) prevent tertiary complications. If we will however have to prevent progressive renal function loss, we will first have to detect these patients in an early phase.

That is not to be achieved by waiting in the hospital. We need to discuss with general practitioners and first line health care workers how these patients should be detected and treated. In that respect, it is the question whether we should measure renal function in subjects with atherosclerotic risk factors, or it may be even better screen ing for proteinuria or preferably microalbuminuria. When we have detected a subject at risk for progressive renal function loss, we should be able to offer him treatment. It is therefore encouraging that in various trials, agents lowering urinary protein loss in patients with proven primary renal diseases have been found effective to delay progressive renal failure. We recently showed (Gansevoort RT et al, Kidney Intl. submitted) that the incidence of ESRD patients due to primary diseases (glomerulonephritis and pyelonephritis) indeed diminished in the Netherlands in the last decade. Starting such treatments in those not known with a primary renal disease may thus also be of help to slow down the continuous increasing incidence of ESRD due to such causes.

Prof Zoccali: Which is presently the main challenge to Preventive Nephrology?

Prof de Jong: As mentioned above, creating programs in the community to detect subjects at risk for ESRD in an early phase, and instruct both the health care workers and the patients at risk on preventive measures.

Prof Zoccali: Could you tell us briefly the story of the PREVEND study?

Prof de Jong: In 1997, we started to screen the entire population of Groningen on albuminuria. All subjects that were positive together with a select sample of those that were negative were further invited for more accurate studies on renal, cardiac and vascular function. That cohort of 8592 subjects has since then been followed every three year on our out-patient unit to study whether having an increased albuminuria (but no diabetes) has similar impact for future renal and vascular damage as in diabetes.

Prof Zoccali: The PREVEND study has provided several new important findings for early diagnosis and prevention of renal dysfunction. Which is the one you repute as the most important?

Prof de Jong: We indeed found that a modest elevation of albuminuria (15-30 mg/day) is associated with glomerular hyperfiltration, while further elevations of albuminuria are related to impaired glomerular hyperfiltration (Pinto-Sietsma et al, JASN 2000; 11: 1182-8). We next showed that subjects with a higher albuminuria at baseline have a more rapid loss of renal function in the years thereafter (Verhave et al KI in press). Albuminuric subjects also have a worse survival, independent of the presence of diabetes, hypertension and hyperlipidemia (Hillege et al, Circulation 2002; 106:777-82). Our hypothesis that an increased albumin loss in the urine has thus similar unfavourable impact in non-diabetics as in diabetes thus seems correct. This is of importance because of all Groningen inhabitants with a positive screening on albuminuria, only 25% was known to be diabetic and/or hypertensive (Hillege et al JIM 2001; 249: 519-526). It was found that age and sex (Verhave et al JASN 2003; 14: 1330-35), smoking (Pinto-Sietsma Ann Int Med 2000; 133: 585-91), obesity (Pinto-Sietsma et al. Am J Kidney Dis 2003; 41: 733-41) and the use of estrogens (Monster et al. Arch Int Med 2001; 161: 2000-5) were also important factors related to an increased albuminuria.

Prof Zoccali: How do you envisage Nephrology in 2010?

Prof de Jong: I hope the huge challenge to detect subjects at risk for ESRD with their subsequent treatment will help to stabilize or maybe to turn down the incidence of new ESRD patients.

Prof Zoccali: Which is the paper that most influenced your research interests?

Prof de Jong: The data of the groups of Mogensen and of Parving that so nicely demonstrated the impact of albuminuria for renal and cardiovascular prognosis in diabetes.

Prof Zoccali: Which advice would you give to a young doctor entering a career in nephrology?

Prof de Jong: Although the studies described above are performed in large groups of subjects, I would emphasize that most new ideas originate from in-depth close monitoring of events in individual patients. Only by close monitoring with an open view for unexpected findings important ideas are born. As such I also remember in 1985 the first renal patients that we treated with an ACE inhibitor as antihypertensive, and how we became aware of the finding that proteinuria fell in those patients!

Prof Zoccali: Which is your favourite hobby?

Prof de Jong: Gardening and visiting museums, especially for modern art.

Prof Zoccali: You are homonym with a first class soccer player, Utrecht team defender. Any football in your life?

Prof de Jong: You are well informed. De Jong is a very common name in the Netherlands, just as de Vries and Janssen. I did not play soccer, just hockey and tennis.