#4735 USEFULNESS OF CYSTATIN C IN MEASURING RENAL FUNCTION AND PREDICTING METHOTREXATE ASSOCIATED TOXICITIES IN PATIENTS WITH RHEUMATOID ARTHRITIS

Abstract

Abstract Background and Aims Rheumatoid arthritis (RA) is a representative chronic disease accompanied by muscle loss, and cystatin C may be more useful than traditional creatinine (Cr) when measuring renal function. RA is affected not only by drug dose but also by side effects of treatment according to renal function. Therefore, we tried to compare the estimated glomerular filtrate rate (eGFR) using cystatin C and Cr and analyze the methotrexate (MTX) associated toxicities after treatment. Method A total of 436 RA patients was enrolled in this study. The eGFR was calculated using the Chronic kidney Disease Epidemiology Collaboration (CKD-EPI) equation based on cystatin C and serum Cr. According to eGFR, CKD stages and drug dosing stages were classified and MTX associated toxicities were evaluated. Results Mean eGFR using the CKD-EPI cr and CKD-EPI cystatin C equations were 95.36 and 89.44 mL/min. In the CKD-EPIcr group, there were 11 patients with eGFR less than 50 mL/min that required dosing reduction, and 38 patients in the CKD-EPI cystatin C group, showing a statistically significant difference (Table 1A). In addition, CKD stage 3B and 4 patients were also higher in the CKD-EPI cystatin C group compared to those in CKD-EPI cr group (Table 1B), and anemia and nephrotoxicity were high in the MTX related toxicity stage upgraded group. Conclusion Our study showed that eGFR by CKD-EPI Cr can be overestimated than that by CKD-EPI cystatin C, and also demonstrated higher MTX associated toxicities in the group, which the stage was changed upward. Therefore, this study suggests that cystatin C is useful predictor in measuring renal function and predicting MTX associated toxicities in RA patients