Comparação de fórmulas para cálculo da taxa de filtração glomerular estimada e seus limiares diagnósticos para doença renal crônica em idosos

Abstract

Chronic kidney disease (CKD) is defined by changes in markers of kidney damage or glomerular filtration rate (GFR) less than 60 ml/min/1.73m2 for a period ≥ 3 months. There is diagnostic difficulty in the elderly patient as there is a physiological decrease in GFR without necessarily having CKD. The association of comorbidities, especially systemic arterial hypertension (SAH) and type 2 diabetes mellitus (DM2) is already well described. Currently, several formulas are available to calculate the estimated glomerular filtration rate (eGFR), some of which are more studied in the elderly population. Current discussions regarding new diagnostic thresholds for CKD in the elderly are also recognized. To evaluate the clinical profile of patients aged ≥ 65 years treated at the CEMEC nephrology outpatient clinic from January 2020 to April 2022, with emphasis on the analysis of serum creatinine, eGFR and comorbidities. In addition to comparing the CKD-EPI, BIS1 and MDRD formulas and the diagnostic threshold of 45 and 60 ml/min/1.73m2. This is an observational, cross-sectional, descriptive, and analytical study. The target population of the study consisted of patients seen at the nephrology outpatient clinic of the Centro de Especialidades Médicas do CESUPA (CEMEC) during the period from January 2020 to June 2022, of both sexes and aged 65 years or older. The tests were performed with the help of SPSS version 24, or GraphPad Prism version 9.3.1 and/or Bioestat 5.4 programs, with a significance level of 0.05. SAH, DM2 and dyslipidemia were the most observed comorbidities. Regarding the values of GFR estimated by the CDK-EPI, BIS1 and MDRD formulas among patients, it was found in all formulas that they were significantly lower in those with SAH, DM2 and CVD. Based on the thresholds of 45 and 60 mL/min/1.73m2 proposed by the CDK-EPI, a significant association was observed between the presence of SAH and DM2 and eGFR values <45 mL/min/1.73m2 and between the presence of SAH and CVD and eGFR values <60 mL/min/1.73m2, by the estimates obtained by BIS1, there was a significant association between the presence of SAH and CVD in patients with eGFR <45 and <60 mL/min/1.73m2 and between the presence of DM2 and eGFR <45 mL/min/1.73m2, using the MDRD formula, there were significant associations between the presence of SAH and DM2 and eGFR <45 mL/min/1.73m2 and the presence of SAH, DM2 and CVD and eGFR <60mL/min/1.73m2. The BIS1 formula showed lower agreement with the others and lower eGFR values, and its use in the elderly population may benefit. The possibility of combining it with the diagnostic threshold of 45 ml/min/1.73m2 is suggested for greater precision in the diagnosis of CKD in the elderly. Using the threshold of 45 ml/min/1.73 m2, there was a decrease in the number of patients diagnosed with CKD by the eGFR criterion, but patients in this group have stronger associations with comorbidities, mainly SAH, DM2 and CVD, regardless of the formula used. We understand the need for further studies comparing morbidity and mortality outcomes in patients diagnosed by the thresholds of 45 and 60 ml/min/1.73m2, in addition to studies analyzing the different formulas in Brazilian population.