Clinical factors increasing discrepancies of renal function assessment with MDRD and Cockcroft-Gault equations in old...

In a daily clinical practice, glomerular filtration rate (GFR) is still estimated on the basis of short MDRD formula, whereas medications' Summaries of Product Characteristics suggest that GFR used for the dosage adjustment should be estimated based on the Cockcroft-Gault (C-G) equation. The aim of the study was to compare eGFR values calculated on the basis of short and full MDRD and C-G equations in PolSenior study participants with decreased eGFR.

We have assessed differences in the estimation of GFR between short and full MDRD, as well as C-G formula, all equations utilizing non-isotope-dilution mass spectrometry-calibrated measurements of serum creatinine, in the community-based population of 760 persons aged 65 years or above (mean age 82 ± 8 years) with estimated GFR < 60 ml/min/1.73 m² (according to short MDRD). In addition, in our analysis, we have included the detailed characteristics of comorbidities and different aspects of mobility and functional performance.

The better concordance, precision, and accuracy with MDRD short formula were found for MDRD_full than C-G equation. In logistic regression analysis, female gender, activities in daily living (ADL) ≤ 4, and age > 80 years diminished, while visceral obesity improved accuracy (P₃₀) of eGFR calculated according to C-G equation as compared to MDRD_short. Similar analysis did not found factors influencing P₃₀ for MDRD_full equation.

In very old subjects, especially females, dependent patients and those with visceral obesity, estimation of GFR based on short MDRD formula should not be used interchangeably with Cockcroft-Gault equation for the medicines dose tailoring.