The Changing Definition of Contrast-Induced Nephropathy and Its Clinical Implications: Insights From the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2)
What is the sensitivity, specificity, and clinical implication of using a ≥25% increase from baseline creatinine, on contrast-induced nephropathy (CIN) detection?
The traditional definition of CIN has been an absolute rise of serum creatinine (Cr) of ≥0.5 mg/dl, although most recent clinical trials have included a ≥25% increase from baseline Cr. The investigators compared the association of the two definitions with risk of death or need for dialysis among 58,957 patients undergoing percutaneous coronary intervention in 2007-2008 in a large collaborative registry. Patients with a pre-existing history of renal failure requiring dialysis were excluded.
CIN as defined by a rise in Cr ≥0.5 mg/dl (CINTraditional) developed in 1,601, whereas CIN defined either as Cr ≥0.5 mg/dl or ≥25% increase in baseline Cr (CINNew) developed in 4,308 patients. Patients meeting the definition of CINNew, but not CINTraditional, were classified as CINIncremental (n = 2,707). Compared with CINNew, CINTraditional was more commonly seen in patients with abnormal renal function, which was more likely to develop in patients with normal renal function at baseline. Compared with CINIncremental, patients meeting the definition of CINTraditional were more likely to die (16.7% vs. 1.7%) and require in-hospital dialysis (9.8% vs. 0%).
The authors concluded that the traditional definition of CIN (a rise in Cr of ≥0.5 mg/dl) in patients undergoing PCI is superior to a ≥25% increase in Cr at identifying patients at greater risk for adverse renal and cardiac events.
This study suggests that the traditional definition of CIN is preferable to the new definition that has been used in most clinical trials. Furthermore, it provides evidence that validates the long-standing definition of CIN based on measurable and meaningful clinical outcomes. A larger study with strict, consistent, and applicable CIN prevention strategies may further clarify this issue, but pending additional data, it appears that a rise in Cr of ≥0.5 mg/dl from baseline should be the standard definition for CIN.
Keywords: Michigan, Exhalation, Acute Kidney Injury, Blue Cross Blue Shield Insurance Plans, Creatinine, Angioplasty, Percutaneous Coronary Intervention, Contrast Media, Renal Dialysis, Renal Insufficiency, Coronary Angiography, Biological Markers, Vitamin A
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