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Article Review/Hyperlink
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Pedrini MT, Levey AS, Lau J, Chalmers TC, Wang PH
The effect of dietary protein restriction on the
progression of diabetic and non-diabetic renal diseases: a meta
-analysis
Ann Int Med
(Mar) 124:627-632 1996

This is a meta-analysis to evaluate the efficacy of dietary protein
restriction on the progression of renal disease in patients with
diabetic and non-diabetic renal diseases. Only five randomized,
controlled studies, with a mean length of follow-up of more than one
year were included for non-diabetic renal disease (a total of 1413
patients). Five randomized controlled or non-randomized crossover
design studies, with a mean length of follow-up of more than 9 months
were included for insulin-dependent diabetic nephropathy (a total of
108 patients). Renal failure or death for non-diabetic renal disease,
and the increase in urinary albumin level (more than 10% from
baseline) or the decline in glomerular filtration rate or creatinine
clearance (more than 1.2 ml/min per year) for diabetic nephropathy,
were selected as the endpoints.
Random-effects model analysis indicated that dietary protein
restriction (0.4-0.6 g/kg of body weight per day) significantly
reduced the risk for renal failure or death (relative risk, 0.67
[95%CI, 0.50 to 0.89]) compared with usual diet in patients with
non-diabetic renal disease. Dietary protein restriction
(0.50-0.85g/kg of body weight per day) significantly slowed the
increase in urinary albumin level or the decline in glomerular
filtration rate or creatinine clearance (relative risk, 0.56 [95% CI,
0.40 to 0.77]) in patients with non-diabetic renal disease. This
apparent beneficial effect of dietary protein restriction did not
seem to be the result of an effect on blood pressure (diabetic and
non-diabetic renal disease) or glycosylated hemoglobin level
(diabetic renal disease only). In summary, dietary protein restriction
effectively slows the progression of both diabetic and non-diabetic
renal diseases.
Comment: This study has several limitations:
1) For non-diabetic renal diseases, the authors used pooled endpoints
(renal failure or death), admittedly for the limited number of
patients in each categories, and showed that dietary protein
restriction significantly decreased the risk for renal disease
progression. However, the use of patient death as the end point biases
the results, since the patient can die without renal failure, and the
beneficial relationship between dietary protein restriction and death
is difficult to explain. Moreover, the exact number of patients who
developed either renal failure or died is not specified.
2) Studies in patients with diabetic renal diseases included small
numbers of patients, varied in design, and did not include renal
failure as the end point. Thus, the results are inconclusive proof
(as mentioned rightly by the authors).
3) Other potential risk factors related to renal disease progression,
such as proteinuria (for non-diabetic renal diseases), underlying
nephropathy, and dyslipidemia are lacking.
4) The possible harmful effects of dietary protein restriction on the
nutritional status of patients with chronic renal disease are not
evaluated.
Thus, I think we are awaiting still conclusive proof that a low
protein diet is beneficial and safe in patients with diabetic and
non-diabetic renal diseases. (Ziad A. Massy, M.D., Hopital Necker,
Paris, France)
The abstract and full text article are available at the ACP Online site.
abstract
The full text article is available at
fulltext
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