Large Swedish study challenges safety of iso-osmolar agent

Patients undergoing coronary interventions with the iso-osmolar contrast agent iodixanol were twice as likely to have renal failure as those who received low-osmolar nonionic contrast media, according to a Swedish retrospective study of more than 70,000 patients.

Swedish hospitals that began using iso-osmolar media in recent years, believing the agents were safer than low-osmolar compounds such as ioxaglate and iohexol, experienced higher rates of renal failure after the switch, said Dr Per Liss, who presented the results Tuesday at the RSNA meeting.

The findings challenge the results of the landmark NEPHRIC trial, which found that patients receiving iodixanol, sold by Amersham as Visipaque, were 11 times less likely to experience contrast-induced nephropathy (CIN). The results were published in the New England Journal of Medicine in February 2003.

In an interim annual report, Amersham reported that in the first half of 2003, when Visipaque was introduced, global sales went up by 32% compared with first half of 2002.

The company attributed the increase to the NEJM study, which triggered an overwhelming and immediate response, according to the company.

"CIN is a big issue," said Liss, head of radiology at Uppsala University Hospital in Uppsala, Sweden. "After the NEPHRIC trial we thought the problem was solved. But contrary to that study, very surprisingly, we found no indication of iodixanol being less harmful to the kidney than ioxaglate or iohexol. We conclude that further prospective randomized trials are needed."

Uppsala University's research was based on two sources-- the Swedish Coronary Angiography and Angioplasty Registry and the national Hospital Discharge Register, which includes data for re-hospitalizations of patients with a diagnosis of renal failure.