Volume-to-creatinine clearance ratio: a pharmacokinetically based risk factor for prediction of early creatinine increase after percutaneous coronary intervention.

This study sought to validate a pharmacokinetically derived measure of the risk of an early increase in serum creatinine after percutaneous coronary intervention (PCI). The ratio of the volume of contrast media to the creatinine clearance (V/CrCl) has been shown to correlate with the area under the curve of contrast media concentration over time. We calculated V/CrCl in 3,179 consecutive patients undergoing PCI. An increase in serum creatinine of >0.5 mg/dl by 24 to 48 h was considered abnormal. Receiver-operator characteristic methods were used to identify the optimal sensitivity and specificity for the observed range of V/CrCl. The predictive value of V/CrCl for the risk of an early increase in creatinine was assessed using multivariable logistic regression. The overall incidence of an abnormal, early increase in creatinine was 1.5%. The mean and median values of V/CrCl for patients with (mean 5.2 +/- 4.4, median 4.3, interquartile range 2.7 to 6.0) and without (mean 3.0 +/- 2.0, median 2.5, interquartile range 1.7 to 3.8) an early creatinine increase were each significantly (p < 0.001) different between groups. Furthermore, there was a significant association between V/CrCl and an early increase in creatinine (overall and trend, p < 0.001). The receiver-operator characteristic curve analysis indicated that a V/CrCl ratio of 3.7 was a fair discriminator for the early creatinine increase (C-statistic 0.69). After adjusting for other known predictors of post-PCI creatinine increase, V/CrCl > or =3.7 remained significantly associated with an early abnormal increase in serum creatinine (odds ratio 3.84; 95% confidence interval 2.0 to 7.3, p < 0.001). A V/CrCl ratio >3.7 was a significant and independent predictor of an early abnormal increase in serum creatinine after PCI in this unselected patient population.