title: The Chronic Kidney Disease Epidemiology Collaboration cystatin C (CKD-EPI-CysC) equation has an independent prognostic value for overall survival in newly diagnosed patients with symptomatic multiple myeloma; is it time to change from MDRD to CKD-EPI-CysC equations?
abstract: OBJECTIVE
  The estimation of glomerular filtration rate (eGFR) in multiple myeloma (MM) is based on equations that use serum creatinine (sCr), such as the Modification of Diet in Renal Disease (MDRD) equation. However, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) group has suggested that eGFR based on both sCr and cystatin C (CKD-EPI-sCr-CysC) is more accurate than other formulae for the estimation of kidney dysfunction. The aim of this study was to prospectively evaluate, for the first time in the literature, the CKD-EPI-sCR-CysC formula in newly diagnosed patients with symptomatic MM.
  
  
  METHODS
  We studied 220 newly diagnosed, previously untreated, patients with symptomatic myeloma and calculated eGFR using the MDRD, the CKD-EPI-sCR, the CKD-EPI-CysC, and the CKD-EPI-sCr-CysC equations.
  
  
  RESULTS
  CKD-EPI-sCr-CysC equation detected more myeloma patients with stage 3-5 renal impairment than the MDRD, CKD-EPI, or CKD-EPI-CysC equations: 45% vs. 39.5%, 42.2%, and 43.1%, respectively (P < 0.01). This was also observed in the elderly patients (>70 yrs), while in patients ≤70 yrs, the CKD-EPI-CysC equation managed to identify higher number of patients with stage 3-5 renal impairment (RI) than the other equations. Furthermore, 63 (28.6%) patients with eGFR values by the MDRD formula were reclassified to higher CKD stages according to CKD-EPI-CysC equation. The median overall survival for all patients was 52 months. In the multivariate analysis, that included International Staging System stage, lactate dehydrogenase (LDH) ≥300 U/L and eGFR for each different equation (as a continuous variable), only eGFR that included CysC, but not sCr had independent prognostic value (P = 0.013) along with high LDH (P = 0.029).
  
  
  CONCLUSIONS
  Our results suggest that equations based on CysC reveal higher number of MM patients with RI compared with equations based only in sCr. Furthermore, the CKD-EPI-CysC formula independently predicted for survival. Based on these data, we suggest that CKD-EPI equations based on CysC should substitute MDRD, as it has been suggested for patients with several other renal disorders.
authors.affiliation: Department of Clinical Therapeutics, National and Kapodistrian University of Athens, Medical School, Athens, Greece.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Terpos
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Christoulas
authors.forename: Efstathios
authors.initials: E
authors.lastname: Kastritis
authors.forename: Eirini
authors.initials: E
authors.lastname: Katodritou
authors.forename: Anastasia
authors.initials: A
authors.lastname: Pouli
authors.forename: Eurydiki
authors.initials: E
authors.lastname: Michalis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Papassotiriou
authors.forename: Meletios A
authors.initials: MA
authors.lastname: Dimopoulos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009101:Multiple Myeloma / Q000097:blood* / Q000150:complications / Q000401:mortality / Q000503:physiopathology; D015999:Multivariate Analysis; D017410:Practice Guidelines as Topic; D011379:Prognosis; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000150:complications / Q000401:mortality / Q000503:physiopathology; D012720:Severity of Illness Index; D016019:Survival Analysis
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D003404:Creatinine; D007770:L-Lactate Dehydrogenase
keywords: Chronic Kidney Disease Epidemiology Collaboration; Modification of Diet in Renal Disease formula; cystatin C; estimated glomerular filtration rate; multiple myeloma; renal dysfunction