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 CIN narrow (rise in serum creatinine ≥0.5 mg/dL) and CIN broad (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. CIN narrow and CIN broad 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 CIN narrow [adjusted OR 3.5, 95% confidence intervals (95% CI) 1.7–7.3; P  < 0.001] and CIN broad (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. © 2013 Wiley Periodicals, Inc.