Unfortunately, multicenter studies with such characteristics are expensive, especially when using assignments to either verum or placebo. Italy pioneered in early studies during the ninetieths assigning patients with chronic glomerulonephritis to ACE inhibition or placebo (AIPRI trial, REIN trials – GISEN initiative). Although relatively small, these trials used composite endpoints in sampling the adequate numbers of kidney outcomes. Later on studies such as the “Lewis study”, and the trials using AT-I-receptor antagonists in type 2 diabetic nephropathy (IDNT, RENAAL, IRMA-2) tested new hypotheses in the prevention of progressive kidney disease.
Another level of evidence was reached by various outcome studies approaching all-cause mortality or death due to cardiovascular disease. Especially the “Besarab study”, but also the MDRD study and the HEMO study have taught us lessons that endpoints in renal patients are of special dimensions and more difficult to control than in non-uraemic patients. Ultimate results of RCTs also showed that one should not rely on observational studies but embarking into straight forward randomization protocols (USRDS wave 2 morbidity and mortality study versus the 4D trial – investigating the value of a statin in respect to outcomes). Ongoing trials, such as the AURORA study and SHARP, will add considerably to the understanding of heart and kidney disease in general and in specific.
What can registries do about this and how can they help to gather knowledge with future trials. Clearly randomization strategies also can be approached with registries as is currently approached by the DCOR study.
Today, it has become apparent that patients with chronic kidney disease resemble constitute considerable proportions of people from the general population (up to 17 %; i.e. Go et al. NEJM 2004). These sample sizes are of interest to approach in future clinical studies since methods are available to identify those at risk for i.e. cardiovascular disease (estimated GFR or cystatin C determination). The future is bright for clinical research in nephrology and we should be prepared in networking within registries or frameworks providing adequate platforms where research money can and will be invested. It is a promising experience for all our colleges already participating in controlled clinical trials that a phenomenon can be observed that encourages us to enrol and motivate a given patient. Whenever a patient with advanced renal failure is assigned to a given treatment he will experience a benefit, irrespective of assignment to either placebo or active treatment. We should find out whether the higher level of care, the greater dose of doctor or the focussed attention of a clinical research nurse will cause the benefit.

Christoph Wanner
Member of the ERA-EDTA Registry Committee