The low-protein diet for chronic kidney disease: 8 years of clinical experience in a nephrology ward

Background: Guidelines indicate that a low-protein diet (LPD) delays dialysis in severe chronic kidney disease (CKD). We assessed the value of these guidelines by performing a retrospective analysis in our renal clinical practice.

Methods: The analysis was performed from 1 January 2010 to 31 March 2018 in 299 CKD Stage 4 patients followed for 70 months in collaboration with a skilled nutritionist. The patients included 43 patients on a controlled protein diet (CPD) of 0.8 g/kg/day [estimated glomerular filtration rate (eGFR) 20-30 mL/min/1.73 m² body surface (b.s.)], 171 patients on an LPD of 0.6 g/kg/day and 85 patients on an unrestricted protein diet (UPD) who were not followed by our nutritionist (LPD and UPD, eGFR <20 mL/min/1.73 m² b.s.).

Results: eGFR was higher in CPD patients than in UPD and LPD patients (21.9 ± 7.4 mL/min/1.73 m² versus 17.6 ± 8.00 mL/min/1.73 m² and 17.1 ± 7.5 mL/min/1.73 m²; P = 0.008). The real daily protein intake was higher in UPD patients than in LPD and CDP patients (0.80 ± 0.1 g/kg/day versus 0.6 ± 0.2 and 0.63 ± 0.2 g/kg/day; P = 0.01). Body mass index (BMI) was stable in the LPD and CPD groups but decreased from 28.5 ± 4.52 to 25.4 ± 3.94 kg/m² in the UPD group (P < 0.001). The renal survival of UPD, LPD and CPD patients was 47.1, 84.3 and 90.7%, respectively, at 30 months (P < 0.001), 42.4, 72.0 and 79.1%, respectively, at 50 months (P < 0.001) and 42.4, 64.1 and 74.4%, respectively, at 70 months (P < 0.001). The LPD patients started dialysis nearly 24 months later than the UPD patients. Diet was an independent predictor of dialysis [-67% of RR reduction (hazard ratio = 0.33; confidence interval 0.22-0.48)] together with a reduction in BMI.

Conclusions: An LPD recommended by nephrologists in conjunction with skilled dietitians delays dialysis and preserves nutritional status in severe CKD.