Análise de métodos de avaliação de ingestão de proteína em pacientes com doença renal crônica na fase não dialítica / Analysis method of assessement of protein intake in patients with chronic kidney disease in non-dialytic stage

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

It has been well described in the literature the errors inherent to the 24 hours urine collection in free-living individuals. Therefore, the assessment of protein intake in nondialyzed chronic kidney disease (CKD) patients by the urinary urea excretion in the 24 hour urine sample, may lead to important errors related to the method itself. In this regard, assessing surrogate methods is of high relevance. To evaluate the accuracy of the dietary methods to estimate the protein consumption in nondialyzed CKD patients and also to assess the agreement between a biomarker of protein intake and dietary methods. In addition, it was also evaluated the agreement between two dietary methods. One hundred and twenty-two nondialyzed CKD patients, who met the eligibility criteria, were included. All participants underwent to antropometric and laboratory assessments, and had the protein intake estimated by three methods: two methods of dietary intake and one dietary biomarker. The dietary intake comprised 4 days of food records (FRec) and 2 days of 24-hour food recall (24hFRecall). For the biomarker, it was evaluated the urinary urea nitrogen excretion in a 24 hours urine sample, which was used in the equation of the protein equivalent of nitrogen appearance (PNA). The software PC-Side was used to estimate the variability of the protein intake in the FRec and 24hFRecall. In addition, specific equations were used to assess the number of days needed to estimate the protein intake with high accuracy in the individual and collective level. In order to evaluate the agreement between the 3 methods, it was used the concordance correlation coefficient (CCC) and the Bland &Altman plot analysis (1986). In the collective level, 4 days FRec and the 2 days of 24hFRecall described the protein intake with an accuracy close the highest acceptable level, being of respectively 0.85 and 0.73. For the individual level, by accepting an intermediate tolerated error of 20% (accuracy 0.8), 6 days of FR and 5 days of 24hFR were needed for the assessment of protein intake. When assessing the agreement between the PNA and the FRec and 24hFRecall, it was observed reduced CCC (<0.3). Likewise, when evaluating the individual differences obtained between the PNA and the FRec and 24hFRecall by the Bland &Altman plot analysis, it was observed a wide concordance limit, which is consistent with the low concordance observed between the methods. Moreover, higher values of CCC (>0.4) were found between the FRec and 24hFRecall. The Bland &Altman plot analysis of these two methods showed more narrows differences, which is consistent with the higher CCC observed. However, this best agreement may be due to an overestimation between the methods. Furthermore, the reduced concordance observed between the PNA and the FRec and 24hFRecall does not mean that the dietary intake methods give biased or unrepresentative measurements of protein intake, nor was that the PNA gave unbiased measurements of protein intake. FRec and 24hFRecall can be used as surrogate methods for the PNA, as an alternative low cost and high applicability method in the clinical routine practice to describe the protein intake.

ASSUNTO(S)

miomarker concordância acurácia biomarcador ingestão de proteína rins - doenças proteínas - análise chronical kidney disease doenças crônicas - nutrição nutricao doença renal crônica protein intake dietary intake methods accuracy concordance inquéritos alimentares

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