Drugs Dosing in Geriatric Patients Depending on Kidney Function Estimated by MDRD and Cockroft-Gault Formulas

According to the current data, regardless of the method used to estimate GFR, the differences between the obtained results should be insignificant and do not imply therapeutic decisions. The aim of this study was to analyze and compare the eGFR results with the estimated creatinine clearance score calculated according to the Cockroft-Gault equation, and to assess the significance of the difference between these two results.

A study group was constituted of 115 patients, of whom 76 were women and 39 men at the age range of 55-93 years, with a median of 79 years. The study analyzed differences in the assessment of kidney function by comparing the results of eGFR assessed by MDRD method obtained from the laboratory with the calculated values of creatinine clearance using the Cockroft-Gault formula, and examining the correlation between the difference D = eGFR -eClCr and BMI and body surface.

In the entire group of patients (N = 115), the significant statistical difference was found between eGFR and eClCr. In the subgroup of patients (N = 45) with the lower baseline eGFR <60, there was no significant difference between eGFR and eClCr, while in the subgroup of patients with baseline eGFR ≥60 (N = 75), there was a significant difference between eGFR and eClCr. The study showed that based on the estimated GFR using both methods (C-G and MDRD), 29.2% and 32.4% of patients, respectively, were incorrectly assigned to given stage of chronic kidney disease.

Proper assessment of kidney function is very important in order to properly drugs dosing, especially to adjust the doses of drugs metabolized by the kidneys in order to avoid or minimize their nephrotoxic effects.