Estimating creatinine clearance: a meta-analysis.

Area of Science:

• Nephrology
• Pharmacokinetics
• Clinical Chemistry

Background:

• Accurate estimation of creatinine clearance (Cl(cr)) is crucial for drug dosing.
• The Cockcroft-Gault equation is widely used but its accuracy with different body weight descriptors and serum creatinine values is debated.

Purpose of the Study:

• To identify the body weight descriptor that most accurately predicts measured Cl(cr).
• To evaluate if rounding serum creatinine concentration (S(cr)) to 1 mg/dl impacts Cl(cr) prediction accuracy.

Main Methods:

• A meta-analysis of 13 trials involving 1197 patients was conducted.
• Compared 24-hour measured Cl(cr) with Cockcroft-Gault estimated Cl(cr) using various body weights and S(cr) values.

Main Results:

• No body weight in the Cockcroft-Gault equation closely estimated measured Cl(cr) (MD 0.43 ml/min).
• Total body weight overestimated Cl(cr) (MD 15.91 ml/min), while ideal body weight underestimated it (MD -5.15 ml/min).
• Rounding S(cr) to 1 mg/dl led to underestimation when using ideal body weight (MD -29.45 ml/min).

Conclusions:

• The Cockcroft-Gault equation with no body weight and actual S(cr) provided the closest estimate of measured Cl(cr).
• For obese patients, using actual body weight with correction factors (0.3 or 0.4) may be appropriate.
• Rounding S(cr) values is not recommended for accurate Cl(cr) estimation.