Purpose: The estimated glomerular filtration rate (eGFR) based on creatinine is crucial for the risk assessment of contrast-associated acute kidney injury (CA-AKI). In recent, the difference between cystatin C-based eGFR (eGFRcys) and creatinine-based eGFR (eGFRcr) has been widely documented. We aimed to explore whether intraindividual differences between eGFRcys and eGFRcr had potential value for CA-AKI risk assessment in patients undergoing elective percutaneous coronary intervention (PCI).
Patients and Methods: From January 2012 to December 2018, we retrospectively observed 5049 patients receiving elective PCI. To determine eGFR, serum creatinine and cystatin C levels were measured. CA-AKI was defined as serum creatinine being increased ≥ 50% or 0.3 mg/dL within 48 h after contrast agents exposure. Chronic kidney disease (CKD) was defined as the eGFR < 60 mL/min/1.73 m².
Results: Approximately half of the participants (2479, 49.1%) had a baseline eGFRdiff (eGFRcys-eGFRcr) between − 15 and 15 mL/min/1.73 m². Restricted cubic splines analysis revealed a nonlinear relationship between eGFRdiff and CA-AKI. Multivariable logistic regression analysis indicated that compared with the reference group (− 15 to 15 mL/min/1.73 m²), the negative-eGFRdiff group (less than − 15 mL/min/1.73 m²) had a higher risk of CA-AKI (OR, 3.44; 95% CI, 2.57– 4.64). Furthermore, patients were divided into four groups based on CKD identified by eGFRcys or eGFRcr. Multivariable logistic analysis revealed that patients with either CKDcys (OR, 2.94; 95% CI, 2.19– 3.95, P < 0.001) or CKDcr (OR, 2.44; 95% CI, 1.19– 4.63, P < 0.001) had an elevated risk of CA-AKI compared to those without CKDcys and CKDcr.
Conclusion: There are frequent intraindividual differences between eGFRcys and eGFRcr, and these differences can be used to forecast the risk of CA-AKI.

Keywords: estimated glomerular filtration rate, contrast-associated acute kidney injury, cystatin C, percutaneous coronary intervention