Article Text

Download PDFPDF

4CPS-016 Predictive performance of glomerular filtration rate equations based on cystatin c, creatinine and their combination in critically ill patients
  1. M Albanell1,
  2. C Bastida1,
  3. Á Marcos-Fendian1,
  4. A Escolà1,
  5. J Mercandal2,
  6. P Castro3,4,5,
  7. D Soy1,5
  1. 1Pharmacy Service, Division of Medicines, Hospital Clinic of Barcelona, Barcelona, Spain
  2. 2Surgical Intensive Care Unit, Anaesthesiology Department, Hospital Clinic of Barcelona, Barcelona, Spain
  3. 3Medical Intensive Care Unit, Hospital Clinic of Barcelona, Barcelona, Spain
  4. 4IDIBAPS, Hospital Clinic of Barcelona, Barcelona, Spain
  5. 5University of Barcelona, Hospital Clinic of Barcelona, Barcelona, Spain


Background and Importance Twenty-four hour urine creatinine clearance (24h-ClCr) remains the gold-standard for estimating glomerular filtration rate (GFR) in critically ill patients; however, it has several drawbacks. Serum creatinine (SCr) is the most frequently used parameter to estimate GFR, however, Cystatin-C (CystC) may reflect GFR changes earlier than SCr.

Aim and Objectives To assess the performance of equations based on SCr, CystC, and their combination (SCr-CystC) for estimating GFR in critically ill patients in comparison to 24h-ClCr.

Material and Methods Retrospective, observational study in a tertiary-care hospital (May 2020 to July 2022). Patients with CystC, SCr and 24h-ClCr measurements within ± 2 days were included. Altered thyroid status and corticosteroids use for >5 days were recorded, as both can alter CystC values.

24h-ClCr was considered the reference method. GFR was estimated using SCr-based equations: CKD-EPI-Cr and Cockcroft-Gault (CG); CystC-based equations: CKD-EPI-CystC and CAPA; and Cr-CystC-based equations: CKD-EPI-Cr-CystC.

Bland-Altman plots were used to compare GFR estimations with 24h-ClCr. Pearson´s correlation coefficients and concordance correlation coefficients (CCC) were calculated. Bias was assessed as (estimated GFR – 24h-ClCr); and precision as the SD of bias. Further analysis was performed with stratified data into 24h-CrCl<60mL/min/1.73m2, 60-130mL/min/1.73m2 and ≥130 mL/min/1.73m2.

Results We included 275 measurements, corresponding to 186 patients. Mean (SD) SCr, CystC and 24h-ClCr were 1.3 (1.1) mg/dL, 1.8 (1.2) mg/L, and 77.0 (57.7) mL/min, respectively. The influence of altered thyroid status (N=22) and corticosteroids therapy (N=64) on CystC values was statistically significant (p:0.0138 and p<0.000, respectively); however, as box-plot were overlapped, we did not exclude them from the analysis.

Bland-Altman plots are shown in figure 1. In the overall population, CKD-EPI-Cr equation showed the lowest bias (2.6) and best precision (33.1). In patients with 24h-CrCl <60mL/min/1.73m2 (N=124), CystC-based equations showed the lowest bias (<3.0) and CKD-EPI-Cr-CystC was the most accurate (13.6). In the subgroup of 60 ≤24h-CrCl <130 mL/min/1.73m2 (N=100), CKD-EPI-Cr-CystC was the most precise (20.9). However, in patients with 24h-CrCl 130mL/min/1.73m2 (N=51), CystC-based equations underestimate GFR, while CG overestimates it (22.8). CKD-EPI-Cr-CystC obtained the highest Pearson´s coefficient (0.742) and CKD-EPI-Cr the highest CCC (0.785).

Abstract 4CPS-016 Figure 1

Bland-Altman plots showing mean differences between estimated GFR and measured 24h-CICr

Conclusion and Relevance Our study showed no evidence of superiority of any equation over others for all evaluated parameters. CystC-based equations were less biased in individuals with impaired renal function (GFR<60 mL/min/1.73m2), CKD-EPI-Cr-CystC performed properly in GFR from 60-130mL/min/1.73m2 and CG in patients >130 mL/min/1.73m2.

Conflict of Interest No conflict of interest

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.