Agreement between equations estimating glomerular filtration rate in elderly nursing home residents and in hospitalised patients: implications for drug dosing.

BACKGROUND

detecting chronic kidney disease (CKD) may have important implications for the management of older and frail people. We aimed at investigating whether clinical setting (nursing home: NH versus hospital: H) affects the agreement between glomerular filtration rate (GFR) values estimated by Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI), Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations.

DESIGN

observational study.

SETTING

comparison between NH residents and H patients.

SUBJECTS

we used data from 177 NH residents, and 439 H patients.

METHODS

the agreement between estimating equations and the odds of a discrepancy >25% between formulas in relation to setting (NH versus H) were investigated.

RESULTS

the agreement between MDRD and CKD-EPI formulas was good either in NH (k = 0.82) or H (k = 0.87) patients, while corresponding figures for CG indicate only a fair agreement with CKD-EPI (k = 0.50 for both populations). Setting (NH versus H) was associated with discordance between MDRD and CKD-EPI (OR = 3.97; 95% CI = 1.75-9.01), but not between CG and EPI (OR = 1.25; 95% CI = 0.87-1.81).

CONCLUSIONS

in NH residents, MDRD and CKD-EPI formulas yield highly concordant GFR values, but CG behaves differently in up to one-third of patients. Such findings have important implications in dosing drugs cleared by the kidney. Setting should be taken into consideration in studies for validation of GFR equations.