The difference between cystatin C‐ and creatinine‐based assessment of kidney function in acute heart failure

Abstract

Aims

Acute heart failure (HF) is associated with muscle mass loss, potentially leading to overestimation of kidney function using serum creatinine‐based estimated glomerular filtration rate (eGFR_sCr). Cystatin C‐based eGFR (eGFR_CysC) is less muscle mass dependent. Changes in the difference between eGFR_CysC and eGFR_sCr may reflect muscle mass loss. We investigated the difference between eGFR_CysC and eGFR_sCr and its association with clinical outcomes in acute HF patients.

Methods and results

A post hoc analysis was performed in 841 patients enrolled in three trials: Diuretic Optimization Strategy Evaluation (DOSE), Renal Optimization Strategies Evaluation (ROSE), and Cardiorenal Rescue Study in Acute Decompensated Heart Failure (CARRESS‐HF). Intra‐individual differences between eGFRs (eGFR_diff) were calculated as eGFR_CysC–eGFR_sCr at serial time points during HF admission. We investigated associations of (i) change in eGFR_diff between baseline and day 3 or 4 with readmission‐free survival up to day 60; (ii) index hospitalization length of stay (LOS) and readmission with eGFR_diff at day 60. eGFR_CysC reclassified 40% of samples to more advanced kidney dysfunction. Median eGFR_diff was −4 [−11 to 1.5] mL/min/1.73 m² at baseline, became more negative during admission and remained significantly different at day 60. The change in eGFR_diff between baseline and day 3 or 4 was associated with readmission‐free survival (adjusted hazard ratio per standard deviation decrease in eGFR_diff: 1.14, P = 0.035). Longer index hospitalization LOS and readmission were associated with more negative eGFR_diff at day 60 (both P ≤ 0.026 in adjusted models).

Conclusions

In acute HF, a marked difference between eGFR_CysC and eGFR_sCr is present at baseline, becomes more pronounced during hospitalization, and is sustained at 60 day follow‐up. The change in eGFR_diff during HF admission and eGFR_diff at day 60 are associated with clinical outcomes.