Factors influencing dialysis outcome: the dialysis dose in perspective.

planted may be better than that of patients who remain Introduction on dialysis. In a centre or country in which there is a vigorous transplantation programme, ‘dialysis alone’ The nature of renal replacement therapy (RRT), the survival is not strictly comparable with that obtained term applied to dialysis and transplantation, has if there is little or no transplantation. changed dramatically in the past decade. The number A point at once obvious and too little addressed in of units offering RRT has multiplied in all European the literature is the glomerular filtration rate (GFR) countries and beyond. These serve areas in which there at which dialysis is commenced. In countries or regions may earlier have been little or no opportunity to treat where facilities are scarce or where the referral to patients in renal failure. At the same time, the stock nephrologists is very late in the course of end-stage of patients on RRT has altered in composition as older renal failure (ESRF), this is often at the terminal and more clinically compromised subjects have entered stage. Elsewhere, there may be considerable renal the treatment programmes. function and the patient is relatively well clinically and None of these changes is uniform, and from country reasonably nourished. Outcome findings are not readily to country, or even within a given country, the delivery comparable in such circumstances. Furthermore, the of RRT differs. So even though there have been, management of late presenting, ill and malnourished overall, improvements in service delivery with concompatients in terms of the ‘dose’ of dialysis needed and itant benefits for survival, it is hardly surprising to find the medical problems which must be defined and dealt that the survival characteristics of the RRT population with is quite different from that of better analysed are themselves not uniform, but the reasons for this patients who enter RRT before terminal renal failure are complex. Despite the intense interest in the chalhas occurred. lenge of improving survival on dialysis, it has remained Clearly, such considerations may account in part for difficult to explain why the results are better in some discrepancies in the survival on dialysis of patients in centres and regions than in others. This report different centres. When any attempt is made to study addresses salient issues. the influence of a given factor on survival, it becomes obvious that even more qualifications apply. General considerations