Table 1.
The major protein restriction randomized controlled trials
| Trial | Population | Planned Intervention | Achieved Protein Intake | ESKD Outcome | Change in GFR or Creatinine Clearance | Adherence/Tolerance of Low-Protein Diet |
|---|---|---|---|---|---|---|
| Rosman et al. 1989 (13) | 228 patients with CrCl 10–60 ml/min | 118 patients were randomly assigned to a LPD group (0.4 or 0.6 g/kg per day); 110 patients were assigned to a control group | Not provided | Dialysis or transplant 6 in LPD group versus 11 in control group | Significant decline in control group versus LPD group based on reciprocal of serum creatinine analysis | Subjective acceptance of LPD was rated “bad” by one third of patients at 3 and 6 months |
| Locatelli et al. 1991 (11) | 456 patients with diabetes CKD | NPD (1 g/kg per day) versus LPD (0.6 g/kg per day), follow-up for 2 years | Dietary protein intake higher than required in LPD: 21% (interview) to 40% (24 hour urine urea calculation) | Doubling in serum creatinine or ESKD development, 27 in LPD group compared with 42 in NPD group (P=0.06) | Change in creatinine 0.029 μmol/L per month in NPD group versus 0.036 μmol/L per month in LPD group | 64 participants withdrew (“lack of cooperation” for 58, “intolerance of low protein food” for 6) |
| Klahr et al. (MDRD) 1994 (16) | Study 1: 585 patients with GFR 25–55 ml/min per 1.73 m2 Study 2: 255 patients with GFR 13–24 ml/min per 1.73 m2 |
LPD (0.58 g/kg per day) versus NPD (1.3 g/kg per day) Very LPD (0.28 ml/kg per day) versus LPD (0.58 g/kg per day) Follow-up 18–45 months |
Mean 1.1 g/kg per day (1–1.3) versus mean 0.7 g/kg per day (0.6–0.8) Mean 0.5 g/kg per day (0.4–0.6) versus mean 0.7 g/kg per day (0.6–0.8) |
The relative risk of ESKD or death was 0.93 (95% CI, 0.65 to 1.33) for the patients assigned to the very LPD compared with those assigned to the LPD | No difference in GFR decline | Differences in protein intake between the dietary groups were achieved by the fourth month of follow-up and remained relatively constant throughout the follow-up period |
| Hansen et al. 2002 (19) | 82 patients with type 2 diabetes and progressive diabetic nephropathy (prestudy GFR decline of 7.1 ml/min per 1.73 m2 per year) | NPD versus LPD (0.6 g/kg per day) based on dietitian advice every 3 months | LPD group achieved mean 0.89 g/kg per day versus prescribed 0.6 g/kg per day | 2 Dialysis or transplant need in 4 in NPD group versus 2 in LPD group | GFR decline was 3.9 ml/min per 1.73 m2 per year in the NPD group and 3.8 ml/min per 1.73 m2 in the LPD group (P=0.87) | Tolerance or quality of life not reported |
| Cianciaruso et al. 2009 (14) | 423 patients with CKD stages 4–5 | LPD (0.55 g/kg per day) versus MPD (0.8 g/kg per day) Follow-up 32 months |
Average protein intakes were 0.73±0.04 g/kg per day for the LPD group and 0.9±0.06 g/kg/d for the MPD | Effects of LPD on death, ESKD, or the composite outcome of both were 1.01 (95% CI, 0.57 to 1.79), 0.96 (95% CI, 0.62 to 1.48), and 0.98 (95% CI, 0.68 to 1.42), respectively | No difference between the two groups | 3 (0.7%) patients met the criteria for protein-caloric malnutrition |
CrCl, creatinine clearance; LPD, low-protein diet; NPD, normal protein diet; CI, confidence interval; MPD, moderate-protein diet.