Adequacy, Nutrition, and Clinical Outcomes

A dequacy, nutrition, and clinical outcomes are three separate and independent aspects ofperi toneal dialysis (PD). They are related, one to the other, but perhaps not as closely as was once thought to be the case. Five years ago, a commonly cited unifying hypothesis was that inadequate clearance on dialysis was the major cause of malnutrition, typically expressed as hypoalbuminemia, and that this malnutrition in turn was the most powerful predictor of adverse outcomes in dialysis patients. Therefore, if higher clearances could be delivered, malnutrition could be reversed and outcomes substantially improved. It is clear that this hypothesis oversimplified a very complicated process. Inadequate dialysis is only one of many causes ofmalnutrition, and it is poorly related to hypoalbuminemia. Outcomes in PD will likely improve when clearances are increased, as appears to have been the case with hemodialysis (HD), but, as presently understood, increased clearances will not cure most malnutrition. If the high rates of morbid ity and mortality seen in dialysis patients are to be improved, a broader approach arising from a better understanding of the pathogenesis of malnutrition and adverse outcomes will be required. In this paper, major developments in these three areas of adequacy, nutrition, and outcomes since the last International Society ofPeritoneal Dialysis meeting in 1995 will be highlighted to put our present state of knowledge into perspective.