Prediction of Creatinine Clearance from Serum Creatinine in Patients with Rheumatoid Arthritis: Comparison of Six Formulae and One Nomogram

Abstract:

The estimation of glomerular filtration rate is important for the medical treatment of patients with rheumatoid arthritis (RA). However, the determination of endogenous creatinine clearance (Clcr) from a 24-h urine collection is an unreliable and time-consuming procedure. We therefore tested the accuracy of six equations and one nomogram for the prediction of Clcr from serum creatinine (Scr) in 38 patients with RA and 20 controls. A positive correlation was found for all methods in the controls (r= 0.83–0.94) and RA patients (r= 0.51–0.69). The methods did not overestimate Clcr in RA. In the RA group the simple formula published by Cockcroft [Clcr = ((140 − age) × body weight)/(72 × Scr), × 0.85 for females] showed the best correlation with the measured Clcr. In RA the Cockroft formula can reliably be used to predict Clcr from Scr.