P-154: Cytatin C: a new biomarker in Multiple Myeloma?

Background Renal impairment in patients with multiple myeloma (MM), according with the International Myeloma Working Group (IMWG), is based on serum creatinine (sCrea) ≥ 2mg/dL or creatinine clearance Methods In this epidemiologic cross-sectional study, 61 consecutives newly diagnosed MM patients (24 women/37 men) from December 2018 to April 2021 were included. In order to compare CKD-EPI and CAPA equations, Cohen’s Kappa statistic was employed. Mann-Whitney T-test and chi-square or Fischer’s exact test were used to evaluate parameters associated to decreased eGFR according to Crea o CC (statistical significance p-value Results A total of 61 newly diagnosed patients with MM (24 women/37 men) with a mean age of 68 years (±11) were included. According to IMWG criteria, kidney disease with increased sCrea was found on 20% of patients (1 woman/11 men), compared to 26% (3 women/13 men) or 39% (7 women/17 men) when CKD-EPI Crea or CKD-EPI CC equations were used, respectively. The degree of agreement between the different equations and the reference method was very good for the CKD-EPI crea equation (Kappa: 0.958 (0.88 - 1.00, 95% CI) and good for the CKD-EPI CC and CAPA equations (Kappa: 0.747 (0.577- 0.917, 95% CI), Kappa: 0.779 (0.619 - 0.939, 95% CI). Patients with decreased GFRe CC showed higher risk factors in comparison with those identified by GFRe Crea, including: age, β2-microglobulin, serum urate, increased monoclonal component in urine, 24 hours urine proteinuria and decreased hemoglobin and albumin. Importantly, GFRe CC methods detected more patients with renal impairment and worse prognosis according to R-ISS-3 criteria by univariate and multivariate analysis (Exp (B) 14,73; rango 1,78- 122,23; 95%CI, P=0,013). Conclusions IMWG criteria may underestimate kidney disease in patients with MM, mostly in women, which could affect to the dose received as well as to its toxicity. Altogether, our data suggest that equations that include CC (CKD-EPI and CAPA) are more accurate to detect hidden kidney disease as well as patients with more and worse prognostic factors.