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

Background

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.

Study Design

Intention-to-treat analysis of follow-up data from a randomized controlled trial.

Setting & Participants

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.

Intervention

LPD versus MPD (protein intake, 0.55 vs 0.80 g/kg/d).

Outcomes

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/m² 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.

Results

Baseline mean age was 61 years, estimated glomerular filtration rate was 16 mL/min/1.73 m², proteinuria had protein excretion of 1.67 g/d, body mass index was 27.1 kg/m², 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.

Limitations

Low event rates for dialysis therapy initiation and death.

Conclusions

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.

Index Words: Chronic kidney disease, low-protein diet, outcomes