Time to abandon nonionic contrast.

E very year, over 1 0 million Intravascular contrast examinations are performed In the United States. A typical dose of 200 mL of high-osmolality Ionic radiographic contrast costs approximately $8 (e.g. , diatrizoate, iothalmate, and others). In comparIson , low-osmolality nonionic contrast costs up to $ 1 70 for equivalent volumes (e.g. , iopamldol. iohexol. and others). If nonlonic contrast were to be used exclusively for radiographic examinations in the United States, the cost of the contrast alone would amount to $1.2 billion (1,2). In this era of limited health care funding. we must determine if this significant extra expense Is justified. In this issue of JASN, Barrett has outlined our current understanding of radiographic contrast-induced nephrotoxlcity (3). The reported risk of developing some degree of contrast-induced renal impairment is between 2 and 6% In unselected patient populations. These differences In reported risk are largely based on the definitions used to define contrast Induced nephropathy (4). Increments in serum creatlnine of 0.5 mg%. although important in research studies, are clinically unimportant. The risk of clinically significant contrast nephrotoxiclty characterized by oliguria or need for dialysis (as determined by pooling the results of the larger clinical trials) after contrast exposure Is much lower, on the order of 7 patIents per 1 0,000 in unselected study populations. The leading and perhaps the only significant risk for the development of contrast neph-rotoxiclty Is underlying renal impairment, and the risk of nephrotoxicity increases exponentially as renal function declines. In patients without preexist-ing renal impairment. clinically important contrast nephrotoxlclty is rare. In a study from our institution in which 443 patients undergoing diagnostic cardiac catheterization were randomly assigned to the nonionic agent iopam-Idol or the ionic agent diatrizoate, there were no differences in mean serum creatinine concentration 48 h after contrast exposure between the two groups (5). Several authors have come to similar conclusions (3). A shortcoming of these studies is that less than 10% of patients enrolled had significant preexisting renal Insufficiency. Barrett et at. specifically addressed the issue as to whether nonionic contrast material has an advantage In preventing contrast-Induced renal dysfunction over ionic contrast material in patients with known renal disease and were unable to find a difference (6). Subsequently. Barrett and Carlisle performed a meta-analysis of studies involving ionic and nonionic contrast media and found a statistically significant difference in neph-rotoxlcity; however, this difference was extremely small and probably of little …