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DIETARY PROTEIN RESTRICTION IN CHRONIC RENAL DISEASE: DISAPPOINTING RESULTS.

Animal studies show that dietary protein restriction protects diseased kidneys. The multicenter Modification of Diet in Renal Disease (MDRD) study tested various dietary and blood pressure interventions in patients with moderate to severe renal disease.

The first trial randomized 585 patients with moderate renal disease to one of four groups: either a normal or low- protein diet plus either moderate or aggressive blood pressure therapy (designed to achieve a target mean arterial pressure of 107 or 92 mm Hg). The second trial randomized 255 patients with severe renal disease to receive either a low- or very-low-protein diet plus either moderate or aggressive blood pressure reduction (as defined above). The overall decline in glomerular filtration rate (GFR) during 2.2 years of follow-up did not significantly differ among the four treatment groups in either trial. The only subgroup that showed a clearly slower GFR decline were patients with heavy proteinuria.

Comment: The authors and editorialists argue that these negative results may be due to the wide range of ages and types of chronic renal diseases in the study population. Further, they suggest that protein restriction and more aggressive blood pressure control would be clearly beneficial if started earlier, or restricted to certain patient subgroups. Perhaps, but that seems to sugar-coat this study's clearly disappointing results.

— AL Komaroff

Published in Journal Watch General Medicine April 15, 1994

Citation(s):

Narins RG; Cortes P. The role of dietary protein restriction in progressive azotemia. N Engl J Med 1994 Mar 31 330 929-930.

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• Medline abstract (Free)

Klahr S et al. The effects of dietary protein restriction and blood- pressure control on the progression of chronic renal disease. N Engl J Med 1994 Mar 31 330 877-884.

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• Medline abstract (Free)