Risk Factors for High Dose Radiation Exposure in Crohnʼs Disease

Abstract

Purpose: Diagnostic imaging is used frequently in patients with Crohn's disease (CD); therefore, CD patients may be exposed to high amounts of radiation from diagnostic imaging in their lifetime. Frequent exposure to radiation increases the incidence of malignancy. The aim of this study was to identify demographic and disease-specific characteristics that are associated with higher diagnostic radiation exposure in patients with CD. Methods: 106 patients with CD who were initiated on anti-TNF or immunomodulator therapy with at least one year of follow-up between 2004 and 2008 were included. All radiologic studies done 1 year before and 1 year after initiation of immunomodulators or anti-TNF therapy were recorded. The cumulative effective dose of radiation over the 2 years was calculated using standardized effective doses. Demographics, disease phenotype, disease duration, and presence of extraintestinal manifestations of disease (EIM) were extracted from a preexisting clinical database. The cohort was divided into quartiles by effective dose of radiation. Logistic regression analysis was performed to identify associations between demographic and disease-specific variables and cumulative effective dose of diagnostic radiation ≥55 mSv (top quartile effective dose of radiation). Results: 86% of the patients were <40 years old at diagnosis. 68% were female. 79% were Caucasian. 32%, 54%, and 14% had ileal, ileocolonic, and colonic disease, respectively. 27%, 34%, and 39% had inflammatory, stricturing, and penetrating disease, respectively. 29% had perianal disease and 29% had EIM. 64% were treated with anti-TNF agents and 38% with immunomodulators. 55% of patients were diagnosed with CD for less than 10 years prior to the study. Exposure to diagnostic radiation did not differ by age, sex, race, age at diagnosis or duration of disease, smoking status, presence of upper tract or perianal disease, presence of EIM or type of medical therapy initiated. Obstructing or penetrating disease was associated with higher exposure to diagnostic radiation (OR 4.84, 95% CI 1.07 to 21.98). There was also a trend to higher radiation exposure in patients with ileal or ileocolonic compared to patients with colonic disease (OR 5.2, 95% CI 0.59 to 45.87). Conclusion: Obstructing and penetrating CD is associated with higher diagnostic radiation exposure compared to patients with inflammatory disease behavior. Ileal and ileocolonic disease location compared to colonic disease location is also likely associated with higher radiation exposure. The use of ionizing radiation in the diagnostic evaluation of CD, especially in patients with complicated disease behavior and small bowel disease, should be minimized in an effort to reduce their lifetime exposure to radiation.