Background: The objective of this study was to determine the efficacy of low protein diets in delaying the need to start maintenance dialysis based on an analysis of published literature.
Methods: The search strategy involved a Medline and Embase search from January 1966 through to June 1999, congress abstracts (American Society of Nephrology since 1990, European Dialysis Transplant Association since 1985, International Society of Nephrology since 1987) and direct contacts with investigators. The selection criteria included randomized trials comparing two different levels of protein intake in adult patients suffering from moderate to severe renal failure, followed for at least 1 year. Patients with diabetic nephropathy were excluded. Seven trials were selected from 40 studies since 1975. A total of 1494 patients were analysed: 753 had received reduced protein intake and 741 a higher protein intake. The numbers of 'renal deaths' (defined as the need for starting dialysis, the death of a patient or kidney transplant during the trial) were collected.
Results: 242 renal deaths were recorded, 101 in the low protein diet and 141 in the higher protein diet group, giving an odds ratio of 0.61 with a 95% confidence interval of 0.46 to 0.83 (P=0.006).
Conclusion: Reducing protein intake in patients with chronic renal failure reduces the occurrence of renal death by about 40% as compared with larger or unrestricted protein intake. The optimal level of protein intake cannot be confirmed from these studies.