Serum cystatin C is independently associated with renal impairment and high sensitivity C-reactive protein in systemic lupus erythematosus

Objectives: In systemic lupus erythematosus (SLE) patients, glomerular filtration rate (GFR) is usually estimated using the modified Cockcroft-Gault (mCG) and Modification of Diet in Renal Disease (MDRD) equations. We aimed to study cystatin C (sCysC) in SLE to assess its agreement with standard renal indices and investigate factors affecting sCysC in SLE. Methods: SLE patients (=4 ACR criteria) and healthy women from Greater Manchester were recruited and clinical assessments were undertaken. SCysC was measured using R&D Systems' ELISA. Agreement between renal measures was assessed using Deming plots and factors associated with sCysC in SLE were examined by multiple linear regression analyses. Results: 178 patients and 68 controls had median (IQR) ages of 53 (46-61) and 50 (39-60) years, respectively. In an age-adjusted analysis, SLE patients had higher sCysC (1.16 [0.98-1.36] vs. 0.950 [0.73-1.13] mg/l; p