Doença renal crônica: validação de equações para estimativa da taxa de filtração glomerular e uso da idade do rim como estratégia de informação ao paciente
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Data
2023-06-27
Autores
Almeida, Wagner Luis da Cruz
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Universidade Federal do Espírito Santo
Resumo
The most important laboratory indicator of chronic kidney disease (CKD) is the glomerular filtration rate (GFR), which is normally measured through endogenous creatinine clearance (CrCl). This method involves long-term urine collection (12 or 24 hours), which can lead to sampling losses and errors. It is possible to estimate urinary ClCr using serum creatinine (SCr) in a casual sample using equations, increasing the viability of the method. Among these, the Modification of Diet in Renal Disease (MDRD-4) and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) are the most used in Brazilian clinical practice. Both mathematically adjust the GFR according to sex, age and skin color, however, the adjustment by race/color has been questioned in highly mixed populations. The prevention and treatment of CKD requires the individual to adopt a healthy lifestyle and be proactive in terms of renal health care, based on receiving clear information from health professionals. However, GFR is a term that is difficult to understand for laypeople, and its use leads to a loss of quality in professional-patient communication. Currently, the transformation of the GFR result into calculated renal age (IRC) is discussed, which is expressed in years, and whose simplicity can increase the understanding of information about renal function. This thesis has as its main objective to verify the agreement between the GFR measured in 12h or 24h and estimated by MDRD-4 and CKD-EPI formulas, evaluating the accuracy of these two equations. Secondarily, the objective is to analyze the applicability of the mathematical adjustment for equations in individuals with black skin and also to use the GFR data estimated by formulas for the development of a new equation for calculating the IRC. Baseline data from the National Health Survey, conducted in Vitória-ES (2012) and from the Longitudinal Study of Adult Health (ELSA-BRASIL) were used. In the PNS, subjects aged 20 to 69 years living in Vitória-ES and the metropolitan region underwent 24-hour urinary and fasting blood collection. In ELSA-BRASIL, we used data from volunteer civil servants aged 30 to 74 years, who performed a 12-hour urine and fasting blood collection. In both populations, GFR was measured using ClCr in urine and estimated using the CKD-EPI and MDRD-4 formulas. The agreement between CrCl and GFR calculated by the formulas was analyzed using the Bland-Altman method. One-way analysis of variance (ANOVA) with race/color factor was used to compare CrCl and GFR means calculated with and without adjustment for race/color. Statistical significance was accepted at p<0.05. In order to create a new equation for calculating the IRC, the equation IRC= [(1/0.9)+(105−GFR)+40 from literature was used as a reference. After analysis of the PNS data (n=272), there was an adequate agreement between the CrCl and the equations, but the adjustment by race/color decreases the accuracy of the latter. In the race/color factor, there was a similarity between groups for CrCl (p=0.21), suggesting that there is no difference in creatinine metabolism as a function of skin color. About the ELSA-Brasil participants with a validated 12-hour urine collection (n=12813), the Bland-Altman diagrams showed that the formulas and CrCl agree with each other, with better accuracy identified for GFR <90ml.min.1.73m2 and that adjusting for race/color increases data dispersion. In this range of GFR, one-way ANOVA of CrCl with race/color factor showed similarity between groups (p=0.27). After validating the formulas, it was found that the decline in GFR was estimated by the CKD-EPI at 0.76 ml/min.1.73m2 /year of life, from the age of 27 in the healthy subsample of the PNS. These data allowed the proposition of the equation 'IRC=[(1/0.76*)*(115.4- CKD-EPI)+27]', with the result expressed in years. It was concluded that MDRD4 and CKD-EPI are adequate formulas for screening CKD in the Brazilian population, and since there is no difference mediated by race/color in urinary creatinine excretion, the adjustment by race/color for the use of these formulas, which increased the dispersion of results, is unnecessary and detrimental to their accuracy. Additionally, it was possible to create a formula for calculating the IRC, to be tested with data from ELSA-BRASIL.
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Taxa de filtração glomerular , Doença renal crônica , Testes de função renal