Preoperative cystatin C predicts contrast-induced nephropathy in PCI patients

Preoperative cystatin C (CysC) is a useful biomarker of renal function after percutaneous coronary intervention (PCI), according to a study. Moreover, high preoperative CysC can predict contrast-induced nephropathy (CIN), a serious complication of PCI, earlier than serum creatinine.

“CysC before PCI may have a higher potential to function as a biomarker for renal function that predicts CIN after PCI when compared with serum creatinine,” the researchers said. “To improve the prognosis of patients undergoing PCI, it is recommended that caregivers monitor patients with high CysC levels more intensively.”

A total of 341 patients with normal renal function were enrolled into the study from December 2014 to December 2015. Participants were then assigned to normal CysC (≤1.03 mg/L) or high CysC (>1.03 mg/L) groups before PCI and were hydrated from 4 hours prior to PCI to 24 hours after the procedure. The researchers monitored function at 48 hours postoperatively and recorded clinical parameters before and after PCI.

No significant between-group difference was observed in preoperative serum creatinine, but preoperative CysC showed a significant difference between the CIN and non-CIN groups (p<0.01). [Singapore Med J 2021;doi:10.11622/smedj.2021002]

In logistic regression analysis, elevated CysC prior to PCI was found to be predictive of CIN (p=0.013). In addition, linear regression models revealed an association between CysC before PCI and renal function after PCI.

“Our findings suggested that preoperative CysC levels positively correlated with serum creatinine levels but negatively correlated with glomerular filtration rate (GFR) and creatinine clearance,” the researchers said. “This indicates that preoperative CysC level may be regarded as a biomarker of renal function.”

The current results were also consistent with those of earlier studies, which reported the association of renal insufficiency at baseline with a higher risk of CIN. [J Am Coll Cardiol 2004;44:1393-1399; Int J Hepatol 2015;2015:309042]

“CysC was more sensitive to renal injury than serum creatinine,” the researchers noted. “Some studies have reported that serum creatinine lags behind a decrease in GFR, so that serum creatinine could not reflect the patient’s renal function precisely.” [Intensive Care Med 2004;30:33-37; Prilozi 2012;33:27-48]

However, CysC was sensitive to early renal injury, having a sensitivity of 89.6 percent and a specificity of 63.6 percent. For instance, CysC level increased earlier than the serum creatinine level when a renal injury had occurred. [Int J Hepatol 2015;2015:309042]

The current study was limited by its lack of follow-up and failure to continuously monitor the fluctuation of clinical parameters. In addition, CysC assessments remain expensive and are not widely available for it to be considered a viable option for routine examinations prior to invasive procedures.

“The most important predictor of CIN is renal function before PCI,” the researchers said. “Serum creatinine is a commonly used biomarker of renal function, but an elevation in serum creatinine lags behind the onset of kidney injury and is not viable for early detection of CIN after PCI.”