Reduction of dietary protein and phosphorus in the modification of diet in renal disease feasibility study

Abstract

Objective and design The Modification of Diet in Renal Disease (MDRD) Feasibility Study was designed to test procedures and evaluate the feasibility of a full-scale clinical trial aimed at assessing the effects of reduction of dietary protein and phosphorus on progression of renal disease. Setting and subjects Ninety-six patients with chronic renal insufficiency were randomly assigned to different diets in one of two studies depending on their glomerular filtration rate. Intervention The diets contained three different protein and phosphorus levels: moderate diet=1.3 g protein per kilogram per day and 16 to 20 mg phosphorus per kilogram per day; low diet=0.575 g protein per kilogram per day and 5 to 10 mg phosphorus per kilogram per day; and very low diet with keto or amino acids=0.28 g protein per kilogram per day and 4 to 9 mg phosphorus per kilogram per day. Eighty-five patients were monitored for at least 6 months; maximum follow-up was 22 months. Main outcome measures Compliance with study diets was measured monthly using urea nitrogen appearance and 3-day diet diaries plus one 24-hour recall. The main outcome measure was change or maintenance of glomerular filtration rate. Statistical analyses performed Data were analyzed by analysis of variance and paired t tests. Results Mean dietary protein intake, as determined by urea nitrogen appearance, decreased significantly in participants assigned to the diets low and very low in protein and phosphorus (P