RESUMEN
BACKGROUND: Accurate assessment of kidney function level is the key to the identification and management of chronic kidney disease (CKD). Glomerular filtration rate (GFR) is the best measure of overall kidney function in health and disease. There is no consensus about the method to be used routinely to measure and/or estimate GFR. The objectives of this study were to assess which method correlates better with creatinine (Cr) clearance, extensively used in medical practice, as well as assessing the efficacy of the modification of diet in renal disease (MDRD) equation, in our population. METHODS: We studied 262 adult out-patients with stable CKD on conservative treatment. GFR was evaluated by Cr clearance, Cockcroft-Gault (CG) formula, the mean of urea and Cr clearances (total clearance (TCl)), the MDRD study equation, with and without the variable for African-Americans (MDRD1) and the simplified one (MDRDs). Data were analyzed by Pearson's correlation coefficient (r) and Bland & Altman plot analysis. RESULTS: Pearson's correlation showed that all methods where similar when compared to Cr clearance. A high correlation was observed between CG and MDRD equations, and TCl and MDRD equations showed the worst correlation. Among the MDRD equations, no differences were found. Bland-Altman plot analysis indicated a concordance among the studied methods. CONCLUSION: The CG formula could replace Cr clearance in our population, being simpler than and equally as sensitive as the MDRD equation.