Lack of Concordance between Worsening Renal Function Defined by Rise in Creatinine Versus Rise in Cystatin C

Abstract

Worsening renal function (WRF) is often defined as a 0.3 mg/dl rise in serum creatinine (sCr) in acute heart failure studies. Cystatin C (CysC) has been proposed as a better marker of glomerular filtration rate (GFR). This study investigates the concordance between WRF defined by either a rise in sCr or a rise in CysC. We determined sCr and CysC levels on day 1 and day 3 in 121 patients, admitted with acute decompensated heart failure. WRF was defined as a 0.3 mg/dl rise in sCr (WRFsCr) or a 0.3 mg/L rise in CysC (WRFCysC) in agreement with previously proposed definitions. In our patient cohort (age 60±14 year, 74% male, EF 31±17%), sCr levels were 1.39 [0.98-2.12] and 1.4 [0.98-1.96] mg/dl and CysC levels were 1.95 [1.42-2.69] and 1.97 [1.42-2.60] mg/L on day1 and day3, respectively. The correlation (Spearman) between sCr and CysC was good at day1 (r=0.81) and day3 (r=0.79) (both p<0.0001). However, the correlation between the change in sCr and CysC from day1 to day3 was less robust (r=0.47). WRFsCr and WRFCysC occured in 14/121 (12%) and 15/121 (12%) patients respectively. However, only 4 patients experienced WRF by both definitions.View Large Image Figure ViewerDownload Hi-res image Download (PPT) There is a poor agreement between WRF defined by a sCr rise or a CysC rise. This observation raises questions regarding the reliability of current definitions of WRF as it may vary by the renal indices to which the changes were determined.