CKD-EPI is the most reliable equation to estimate renal function in patients with systemic lupus erythematosus.

BACKGROUND

No study has determined the best equation for estimating renal function in patients with systemic lupus erythematosus (SLE), starting from a gold standard test.

OBJECTIVE

To evaluate the performance of cistatin/creatinine based equations for estimating renal function in patients with SLE.

METHODS

We conducted two phases: the first phase included 14 patients in which iothalamate clearance was used to determine the glomerular filtration rate (GFR) and compared with different equations based on cystatin C and/or creatinine. In the second phase, we used the best equation (a cystatin and creatinine-based equation) as "reference standard" to compare 5 creatinine-based equations in 55 patients with SLE.

RESULTS

In the first phase the equation developed by Stevens and colleagues (based on creatinine and cystatin C), was the best equation. In phase 2, the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation was the best equation with bias of -2. 1 ml/min/1.73, accuracy (P30) of 94.5% and precision (interquartile range of differences) of -2.1 ml/min/1.73.

CONCLUSIONS

Our data suggest that CKD-EPI is the best creatinine-based equation to estimate GFR in patients with SLE.