Evaluation of Chronic Kidney Disease Epidemiology Collaboration equation to estimate glomerular filtration rate in scleroderma patients

Objective. Renal involvement in SSc is often subclinical and chronic kidney disease (CKD) develops, with slow worsening of glomerular filtration rate (GFR). The present investigation was undertaken in order to study how well the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) correlates with measured GFR (mGFR) in a group of SSc patients with serum creatinine (sCr) in the normal range. Methods. Forty-one scleroderma patients (37 females and 4 males) with a median age of 46 years were enrolled. GFR was measured using technetium-99 m DTPA (Tc-99 m DTPA). The modified Cockroft-Gault formula, 4- and 7-variable Modification of Diet in Renal Disease (MDRD) and CKD-EPI equations were used for estimated GFR (eGFR). Results. mGFR showed a median value of 84 ml/min (range 32.8-121.2 ml/min). Seven patients had reduced GFR (< 60 ml/min), 19 had GFR within 60-90 ml/min and 15 had GFR > 90 ml/min. The results showed mild correlation between the BSA-modified Cockroft-Gault and mGFR (P > 0.05), mild statistically significant correlation with 4-variable MDRD (P < 0.05), high statistically significant correlation with 7-variable MDRD (P = 0.01), but the greatest correlation was obtained using CKD-EPI (P = 0.002). No correlation with age, disease duration or subset of disease was found. Conclusions. In scleroderma patients with normal sCr value, CKD-EPI is a useful formula to assess GFR.