Renal Function in Older Hospital Patients Is More Accurately Estimated Using the Cockcroft-Gault Formula Than the Modification Diet in Renal Disease Formula

OBJECTIVES: To compare the accuracy of the two most popular creatinine clearance (CrCl) estimation formulae (Cockcroft‐Gault (CG) and Modification Diet in Renal Disease (MDRD)) in older hospitalized patients. DESIGN: Prospective, cross‐sectional, observational study. SETTING: Two hospital geriatric wards. PARTICIPANTS: Consecutive patients aged 70 and older with an indwelling urinary catheter for the purpose of care. MEASUREMENTS: CrCl was determined according to three methods: measured CrCl from plasma and urine creatinine and 24‐hour urine volume, CG (CG‐CrCl), and MDRD (MDRD‐CrCl). Results were expressed as median and interquartile range (IQR). Moderate and severe renal impairment were defined as a CrCl between 30.0 and 59.9 mL/min and less than 30.0 mL/min, respectively. RESULTS: One hundred twenty‐one patients were included (46% male). Mean age was 86.1±6.7 (range 72–100). Median measured CrCl was 43.8 mL/min (IQR 33.6–61.1 mL/min), CG‐CrCl was 40.9 mL/min (IQR 31.0–52.6 mL/min), and MDRD‐CrCl was 61.3 mL/min (IQR 49.4–77.0 mL/min). The biases of CG‐CrCl and MDRD were −3.5±22.5 and 20.1±28.2, respectively (P