Genetics help predict adverse reactions to CT contrast agents

Patients with a family or personal history of allergic reactions to contrast media are in danger of experiencing future reactions, according to a study published Sept. 3 in Radiology

About half of the 88 million CT scans performed each year in the U.S. involve the use of iodinated contrast media (ICM), wrote co-lead author Min Jae Cha, MD, of Chung-Ang University’s Department of Radiology in Seoul. While most reactions are mild, some can be life-threatening. Furthermore, there has been little done to identify those at risk and prevent subsequent reactions. 

"We wanted to emphasize in our study the importance of premedication and change of iodinated contrast media type as useful preventive measures to prevent recurrent hypersensitivity reaction," said study co-lead author Min Jae Cha, MD, from the Department of Radiology at Chung-Ang University Hospital in Seoul, in a news release. "Hypersensitivity reactions to iodinated contrast media are not rare, but many of them are still preventable."

Cha and colleagues analyzed the data of 196,081 patients (average age of 59) who received a CT scan with ICM at one of seven participating institutions.

In total, 1,433 or .73% of patients experienced hypersensitivity reaction (HSR). A majority were considered mild, but 16.8% were classified as moderate to severe.

The researchers noted a number of predictors of such reactions: a patients history of an ICM-related HSR, hyperthyroidism, drug allergy, asthma and other allergic diseases and a family history of ICM-related HSRs. Using antihistamines and switching to an iodinated contrast media with a different safety profile helped reduce reactions from recurring.

The researchers will study this genetic link to ICM-related HSRs and incorporate their findings into a nationwide South Korean registry to help prevent recurrent reactions.

"We hope that we can establish a systematic nationwide integrated registry for ICM-related HSRs in Korea soon, and our study could be a first step toward that goal," Cha said. "Large-scale and long-term registries involving continuous data collection with standardized protocols will help us unravel all aspects of the contributors to the occurrence and recurrence of hypersensitivity reactions to iodinated contrast media."