DDW 2009: Patients With IBD at Risk for Extremely High Levels of Radiation Exposure

Martha Kerr

June 02, 2009

June 2, 2009 (Chicago, Illinois) — Patients with inflammatory bowel disease (IBD), particularly those with Crohn's disease (CD), are at potential risk for dangerously high levels of radiation exposure.

In reporting their findings here at Digestive Disease Week 2009, Canadian researchers primarily attributed the excess exposure to computed tomography (CT) scans, sometimes performed excessively, they say, during diagnosis and for monitoring disease status.

Karen Kroeker, MD, a fellow in the Division of Gastroenterology at the University of Alberta in Edmonton, and colleagues counted the total number of abdominal radiographic studies for 392 CD patients and 195 ulcerative colitis (UC) patients between September 2003 and September 2008. They calculated the amount of ionizing the patients received in millisieverts (mSv).

The average radiation exposure was 2.77 mSv per patient per year for CD patients and 1.77 mSv per patient per year for UC patients.

Radiation exposure was 159% above background levels for CD patients and 39% above background levels for UC patients.

"Three quarters of the radiation exposure from abdominal imaging for both CD and UC patients was from CT scans," Dr. Kroeker told Medscape Gastroenterology in an interview prior to her presentation. "One third of CD patients had abdominal or pelvic CT scans, compared with one fifth of UC patients."

The average age of CD patients was 40 years (range, 15 - 84 years) and of UC patients was 39 years (range, 17 - 77 years). The average age of patients who had undergone CT scans was 42 years for CD patients and 36 years for UC patients.

Dr. Kroeker's team found that 34% of the CT scans for CD patients and 41% for UC patients were performed in the emergency department. In addition, 67% of CD patients were subsequently admitted, compared with only 38% of UC patients.

The most common reasons for CT scans in CD patients were to exclude abdominal abscess (26%), for unexplained abdominal pain (14%), and to exclude bowel obstruction (12%). For UC patients, the most common reasons were to exclude renal colic (24%) and for unexplained abdominal pain (18%).

"Clinicians need to be more judicious in their use of CT scans in IBD patients," Dr. Kroeker advised. "It isn't reasonable to think we can eliminate them entirely, but we need to consider if we can get the information we need through other procedures, blood tests . . . even conventional x-rays have lower levels of radiation . . . and we shouldn't overlook the value of a careful history and physical examination."

"Distinguishing between UC and CD could prevent the unnecessary use of CT scan," Dr. Kroeker continued. "We need them to assess abscesses, stricturing disease, and possible bowel obstruction, and it may help in determining if surgery is needed or not, but it isn't needed for all cases of abdominal pain. Check the patient's record. A CT scan may have been done recently, and we have to consider if doing another one will really add useful information."

"The pros and cons [of CT scanning] have to be weighed carefully," Sunanda V. Kane, MD, professor of medicine in the Department of Gastroenterology and Hepatology at the Mayo Clinic in Rochester, Minnesota, told Medscape Gastroenterology. "[Magnetic resonance imaging] may be a better test. We have to think about what a CT scan can do and what kind of information it gives us vs what other tests can give us."

Dr. Kane was the moderator of a panel on IBD, during which Dr. Kroeker presented her findings.

"These findings are especially important given the age of the patients. Some of them are very young, when radiation can have especially pronounced adverse effects," Dr. Kane pointed out.

The study did not receive commercial support. Dr. Kroeker and Dr. Kane have disclosed no relevant financial relationships.

Digestive Disease Week (DDW) 2009: Abstract 650. Presented June 1, 2009.

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