Comparison between Cystatin C- and Creatinine-Estimated Glomerular Filtration Rate in Cardiology Patients

Area of Science:

• Nephrology
• Cardiology
• Clinical Chemistry

Background:

• Glomerular filtration rate (GFR) estimation is vital for diagnosing kidney disease, predicting patient risk, and guiding drug dosages.
• Both cystatin C and creatinine are commonly used biomarkers for GFR estimation.
• Discrepancies in GFR estimation can impact clinical decision-making, particularly in cardiac patients.

Purpose of the Study:

• To investigate the differences between estimated GFR (eGFR) calculated using cystatin C and creatinine in a diverse cardiology patient population.
• To assess the clinical implications of these differences on patient categorization and risk stratification.

Main Methods:

• An observational, cross-sectional study was conducted involving 5,678 cardiology patients across various care settings (outpatient, ward, CCU, advanced CCU).
• Estimated GFR was calculated using both cystatin C and creatinine (CKD-EPI) from the same laboratory requests.
• Data were analyzed to compare the eGFR values obtained from the two methods.

Main Results:

• Median creatinine eGFR was consistently higher than median cystatin C eGFR, with a difference of approximately 10 ml/min/1.73 m(2) across all care levels.
• For patients with a cystatin C eGFR below 60 ml/min/1.73 m(2), creatinine eGFR often placed them in a less advanced kidney disease category.
• The observed differences were independent of the level of care provided to the cardiology patients.

Conclusions:

• Significant differences exist between creatinine and cystatin C eGFR in cardiology patients.
• Clinicians must be aware of the specific biomarker used for eGFR reporting to prevent misinterpretation of results.
• Understanding these differences is critical to avoid potential under- or over-medication and requires further research to establish the optimal GFR estimation method for cardiology units.