Volume-to-creatinine clearance ratio in patients undergoing coronary angiography with or without percutaneous coronary intervention: implications of varying definitions of contrast-induced nephropathy.

OBJECTIVES: Whether predicting the risk of early serum creatinine rise using the ratio of the volume of contrast media administered to the estimated creatinine clearance (V/CrCl) is applicable to the broader definition of contrast-induced nephropathy (CIN) (≥0.5 mg/dL absolute and/or 25% relative increase from baseline serum creatinine) is unknown.

BACKGROUND: A V/CrCl ≥4 has been proven to predict the risk of ≥0.5 mg/dL postprocedural absolute rise in serum creatinine.

METHODS: A total of 722 patients undergoing coronary angiography ± percutaneous coronary intervention (PCI) between March 2011 and October 2011 with paired serum creatinine determinations at preprocedure and within 72-hr postprocedure were analyzed. The V/CrCl ratio was calculated by dividing the volume of contrast received by the patient's creatinine clearance. CIN using different definitions was termed as CINnarrow (rise in serum creatinine ≥0.5 mg/dL) and CINbroad (rise in serum creatinine ≥0.5 mg/dL and/or ≥25% increase in baseline serum creatinine).

RESULTS: The mean age was 66 ± 11 years and the mean baseline serum creatinine was 1.1 ± 0.8 mg/dL. Patients with V/CrCl ≥4 were significantly older and more frequently underwent ad hoc PCI compared with those with V/CrCl <4. CINnarrow and CINbroad were observed in 13 versus 3% (P < 0.001) and 23 versus 11% (P < 0.001) of patients with or without V/CrCl ≥4, respectively. After statistical adjustment, a V/CrCl ratio ≥4 remained significantly associated with the risk of both CINnarrow [adjusted OR 3.5, 95% confidence intervals (95% CI) 1.7-7.3; P < 0.001] and CINbroad (adjusted OR 2.5, 95% 1.6-3.9; P < 0.001).

CONCLUSIONS: A volume-to-creatinine clearance ratio ≥4 significantly predicts the risk of early postprocedural rise in serum creatinine regardless of the CIN definition adopted.