Effect of a Low- Versus Moderate-Protein Diet on Progression of CKD: Follow-up of a Randomized Controlled Trial

Abstract

Whether low-protein-diet (LPD) as opposed to moderate-protein-diet (MPD) regimens improve the long-term survival of patients with chronic kidney disease (CKD) or induce protein-caloric malnutrition is unknown. Intention-to-treat analysis of follow-up data from a randomized controlled trial. 423 patients with CKD (stages 4-5) were randomly assigned between January 1999 and January 2003 and followed up until December 2006 or death. The first phase of follow up was from January 1999 to June 2004; additional follow-up was from July 2004 to December 2006. LPD versus MPD (protein intake, 0.55 vs 0.80 g/kg/d). Protein-caloric malnutrition (defined as the occurrence of 1 of the following: loss of body weight > 5% in 1 month or 7.5% in 3 months or body mass index < 20 kg/m(2) with serum albumin level < 3.2 g/dL and normal C-reactive protein level [<0.5 mg/dL]), dialysis, death, or the composite outcome of dialysis and death. Baseline mean age was 61 years, estimated glomerular filtration rate was 16 mL/min/1.73 m(2), proteinuria had protein excretion of 1.67 g/d, body mass index was 27.1 kg/m(2), protein intake was 0.95 g/kg/d, and there were 57% men. Duration of follow-up was 32 months (median, 30 months; 25th-75th percentiles, 21-39). Average protein intakes were 0.73 +/- 0.04 g/kg/d for the LPD and 0.9 +/- 0.06 g/kg/d for the MPD. 3 patients (0.7%) met criteria for protein-caloric malnutrition. 48 patients died (11%), 83 initiated dialysis therapy (20%), and 113 (27%) reached the composite outcome. In unadjusted Cox survival analyses, effects of the LPD on these outcomes were 1.01 (95% CI, 0.57-1.79), 0.96 (95% CI, 0.62-1.48), and 0.98 (95% CI, 0.68-1.42), respectively. Low event rates for dialysis therapy initiation and death. Most patients, who were regularly followed up in CKD clinics, were acceptably adherent to the prescribed dietary protein intake restrictions; the LPD and MPD did not lead to protein wasting; and the LPD did not decrease the risk of death or dialysis therapy initiation compared with the MPD.