Does nutritional intervention in protein-energy malnutrition improve morbidity or mortality?
Although there is an association between malnutrition and a poor clinical outcome, it does not necessarily follow that providing nutrients to such patients will improve the outcome. In fact, a number of prospective randomized controlled trials have not been able to demonstrate that nutritional support does, in general, improve morbidity or mortality. Very few such trials have been performed in patients with renal disease. Three studies in patients with acute renal failure have suggested that patients receiving parenteral nutrition using essential amino acids as the nitrogen source have better outcomes than do patients receiving equicaloric amounts of glucose, but these studies cannot exclude the possibility that the intravenous infusion of high concentrations of dextrose is detrimental. Small studies have suggested that the provision of perdialytic nutrient infusions or enteral nutrient supplements can improve measurements of nutritional status, but none of these trials described the effect of the nutritional intervention on morbidity or mortality. Two small trials have raised the possibility that supplemental ketoacids may retard the progression of chronic renal failure. There is a need for large randomized controlled trials to establish or refute the efficacy of nutritional support in renal disease. Such trials should include a control group that is not receiving any nutritional support.