Cystatin C and eGFR: novel biomarkers for renal impairment diagnosis and two-year progression-free survival in multiple myeloma.

To evaluate cystatin C (CysC) and estimation of glomerular filtration rate (GFR) calculated using the formula, CKD-EPI-CysC (eGFR) for renal impairment diagnosis and predicting the prognosis of patients with multiple myeloma (MM). One hundred-fourteen patients with MM and 38 healthy individuals were recruited for the study. Data on clinical characteristics and renal function-related biochemical indicators were collected and analyzed. Patients with MM had increased levels of CysC (1.25 (0.97-2.31) vs. 0.84 (0.80-0.92), respectively,  < 0.001) and decreased levels of eGFR (53.0 (24.4-81.1) vs. 97.2 (87.0-104.5), respectively,  < 0.001), compared with healthy individuals. There were significantly more patients with elevated CysC levels than with elevated sCr levels (64.9% vs. 41.2%, respectively,  < 0.001). The CKD-EPI-CysC formula detected more patients with eGFR < 60 ml/(min × 1.73 m) than the CKD-EPI-sCr formula (52.63% vs. 37.72%, respectively,  < 0.001). Correlation analysis found that only CysC, eGFR, and eGFR strongly correlated with β-microglobulin in group ISS-I. Logistic regression analysis was used to screen CysC ( = 1.495, 95%  = 1.097-2.038,  = 0.011) and eGFR ( = 0.980, 95%  = 0.967-0.993,  = 0.003) as independent prognostic indicators for 2-year-progression-free survival (PFS) of patients with MM. Receiver operating characteristic curve analysis found that CysC values >1.70 mg/L had 67.6% sensitivity and 65.2% specificity and eGFR values <38.62 ml/(min × 1.73 m) had 65.2% sensitivity and 67.6% specificity for 2-year PFS of patients with MM. In summary, CysC and eGFR were more sensitive than sCr and eGFR for predicting renal impairment in patients newly diagnosed with MM. Increased CysC and decreased eGFR levels were effective predictors of 2-year PFS of patients with MM.