Serum cystatin C is independently associated with renal impairment and high sensitivity C-reactive protein in systemic lupus erythematosus
Chew, C.; Pemberton, P.W.; Husain, A.A.-M.; Haque, S.; Bruce, I.N.
Clinical and Experimental Rheumatology 31(2): 251-255
2013
ISSN/ISBN: 0392-856X PMID: 23306163 Document Number: 664926
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. 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. 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<0.0001) and within SLE those with a history of lupus nephritis had higher sCysC (1.31 [1.10-1.66] vs. 1.11 [0.95-1.29] mg/l; p<0.005). SCysC correlated positively with serum creatinine, and inversely to renal measures (r=-0.530; p<0.0001 [mCG], and r=-0.620; p<0.0001 [MDRD]). There was closer agreement between the two eGFR measures than between either eGFR measures and sCysC. In addition to age and serum creatinine, a multivariate analysis (β, p) found that high-sensitivity C-reactive protein (hs-CRP) (0.03, 0.026) was also independently associated with sCysC in SLE. In SLE, sCysC may be influenced by low grade inflammation as well as by renal dysfunction. Therefore, SCysC should not supplant current assessment of renal dysfunction in SLE.