Renal function assessment in patients with systemic lupus erythematosus

Area of Science:

• Nephrology
• Rheumatology
• Clinical Chemistry

Background:

• Glomerular filtration rate (GFR) assessment in Systemic Lupus Erythematosus (SLE) patients is understudied.
• National Kidney Foundation (NKF) guidelines recommend GFR estimation equations, yet Creatinine Clearance (CCl) remains prevalent among rheumatologists.

Purpose of the Study:

• To evaluate and compare various equations for estimating GFR in SLE patients.
• To determine the most accurate and reliable method for GFR assessment in this population.

Main Methods:

• Compared Simplified MDRD study equation (sMDRD), CCl, Cockcroft Gault (CG), CG with ideal weight (CGi), Mayo Clinic Quadratic (MCQ), and CKD-EPI.
• CKD-EPI served as the reference standard, with analyses including bias, correlation, sensitivity, specificity, PPV, NPV, P30, and ROC curves.
• Assessed the adequacy of 24-hour urine collection for GFR measurement.

Main Results:

• The CKD-EPI equation was the reference standard.
• sMDRD showed the best sensitivity and NPV for GFR < 60 ml/min/1.73 m², while MCQ had the best PPV and specificity.
• sMDRD demonstrated the lowest bias, whereas CCl exhibited the highest bias and was deemed inadequate; CGi outperformed CG.

Conclusions:

• Creatinine clearance (CCl) is not an adequate method for estimating GFR in SLE patients.
• The CKD-EPI equation is recommended as the reference standard for GFR estimation in SLE.
• Utilizing ideal body weight (CGi) improves GFR calculation accuracy with the Cockcroft-Gault equation in SLE patients.