Positive effects of protein restriction in patients with chronic kidney disease

The potential benefit or harm of low-protein diets (LPDs) for patients with chronic kidney disease has been debated. This study sought to investigate the effects of treatment with LPDs on nutritional markers, morbidity, and survival during subsequent dialysis. A second objective was to evaluate the effect of LPDs on renal function and the start of dialysis.

This was a retrospective study of medical records.

The setting was an outpatient nephrology and dialysis clinic.

One-hundred twenty-two renal patients were recruited from the central dialysis registry of one clinic. The patients had been followed by a nephrologist for > or =6 months before dialysis. Sixty-one patients were treated with LPDs, and an equal number of control patients not treated with LPDs were matched for sex, age, dialysis modality, diabetes, and start of dialysis.

Main outcome measures included weight and weight change, serum albumin, glomerular filtration rate, morbidity, and mortality.

There was less mean weight loss in the LPD group the year before dialysis (0.14 kg/month, compared with the control group at 0.36 kg/month, P < .05). The level of serum albumin was higher in the LPD group at the start of dialysis (P < .01). The mean rate of progression during the 6 months before dialysis was lower in the LPD group (4.1 mL/min/year) than in the control group (13.4 mL/min/year) (P < .001). The LPD group had fewer days of hospitalization at the start of dialysis than the control group (8.2 vs 15.4 days, respectively, P < .01). There was no difference in mortality between groups 1, 2, or 5 years after starting dialysis.

Low-protein diets can reduce patient morbidity, preserve renal function, relieve uremic symptoms and improve nutritional status. The results suggest that LPDs can postpone the start of dialysis for 6 months, and entail substantial cost-savings. Low-protein diets should be used more generally in the renal community.