Hey guys I thoughtI'd go and put this on here... I had to go register at the website and click around to find the article, but here's a user friendly version:
Certain Patients With Crohn's Disease Are at Risk for Radiation Exposure From CT Scans CME
News Author: Laurie Barclay, MD
CME Author: Penny Murata, MD
Disclosures
Release Date: May 1, 2008; Valid for credit through May 1, 2009
Credits Available
Authors and Disclosures
Laurie Barclay, MD
Disclosure: Laurie Barclay, MD, has disclosed no relevant financial relationships.
Penny Murata, MD
Disclosure: Penny Murata, MD, has disclosed no relevant financial relationships.
Brande Nicole Martin
Disclosure: Brande Nicole Martin has disclosed no relevant financial information.
May 1, 2008 — Certain groups of patients with Crohn's disease were at risk for high levels of radiation because of computed tomographic (CT) examinations, according to the results of a study reported in the April 28 Online First issue of Gut.
"Exposure to diagnostic radiation may be associated with increased risk of malignancy," write Alan N. Desmond, from Cork University Hospital, National University of Ireland, and colleagues. "The aims of this study were: (a) to examine patterns of use of imaging in Crohn's disease; (b) to quantify the cumulative effective dose (CED) of diagnostic radiation received by patients; and (c) to identify patients at greatest risk of exposure to high levels of diagnostic radiation."
At a tertiary center, 409 patients with Crohn's disease had retrospective calculation of CED from imaging performed between July 1992 and June 2007. High exposure was defined as a CED of more than 75 milli-Sieverts (mSv); this exposure level has been associated with a 7.3% increased risk for cancer mortality. Of 399 patients with complete data, 45 were excluded: 20 who attended the practice outside of the study period, and 25 who were mostly managed at other centers.
During the study, CT use increased significantly, accounting for 77.2% of diagnostic radiation. In 15.5% of patients, CED was greater than 75 mSv. Mean CED for all patients was 36.1 mSv.
Factors linked to high cumulative exposure were age younger than 17 years at diagnosis (hazard ratio
, 2.1; 95% confidence interval [CI], 1.1 - 4.1); upper gastrointestinal tract disease (odds ratio [OR], 2.4; 95% CI, 1.2 - 4.9); penetrating disease (OR, 2.0; 95% CI, 1.0 - 3.9); and need for treatment with intravenous corticosteroids (OR, 3.7; 95% CI, 2.0 - 6.6), infliximab (OR, 2.3; 95% CI, 1.2 - 4.4), or more than 1 surgical procedure (OR, 2.7; CI, 1.4 - 5.4).
"Identifiable subsets of patients with Crohn's disease are at risk of exposure to significant amounts of diagnostic radiation," the study authors write. "Given the background risk of neoplasia and exposure to potentially synergistic agents such as purine analogues and other immune modulators, specialist centres should develop low-radiation imaging protocols."
Limitations of this study include inability to retrospectively measure the actual effective dose incurred by the cohort during the 15-year study period and inability to determine a causal link between malignant neoplasms and diagnostic radiation exposure.
"Computed tomography imaging offers many advantages in the assessment of complicated Crohn's disease: widespread availability; high sensitivity and specificity for detection of luminal and extra-luminal disease; rapid acquisition of images with high spatial and temporal resolution; and a shorter over-all acquisition time compared to conventional enterography and MRI [magnetic resonance imaging]," the study authors conclude. "Strategies to reduce the effective dose of radiation incurred by patients undergoing CT imaging can be employed without sacrificing image quality and should be considered for all patients, particularly those who are likely to require multiple examinations. . . . With increasing awareness of radiation exposure due to CT imaging, and improving availability of MRI [magnetic resonance imaging] facilities, it is likely that MR [magnetic resonance] enterography will emerge as an important diagnostic tool in the routine assessment of patients with Crohn’s disease."
The study authors are supported in part by Science Foundation Ireland, the Health Research Board of Ireland, and the European Union.
Gut. Published online April 28, 2008.
Clinical Context
Patients with Crohn's disease undergo frequent imaging studies for diagnosis and monitoring, exceeding the number of imaging studies needed for those with other types of inflammatory bowel disease, as reported by Newnham and colleagues in the October 1, 2007, issue of Alimentary Pharmacology & Therapeutics. The need for repeated imaging studies in patients with Crohn's disease raises concerns for the increased risk for the development of malignant tumors. According to Cardis and colleagues in the April 2007 issue of Radiation Research, a CED of ionizing radiation greater than 75 mSv has been linked to a 7.3% increase in mortality from all cancers.
This study examines the pattern of diagnostic imaging use in patients with Crohn's disease, the CED of diagnostic radiation, and the factors linked with high exposure to diagnostic radiation.
Study Highlights
* Data for 354 of 409 patients with Crohn's disease identified from a tertiary referral center in a 15-year study period were examined.
* Exclusion criteria were incomplete data, lack of attendance during the study period, and primary management at other sites.
* 167 were men and 187 were women.
* Average age at enrollment was 32.2 years (age range, 8.6 - 78.3 years).
* Mean follow-up was 6.7 years (range, 0.1 - 14.5 years).
* By the end of the study, 271 (76.6%) were being observed, 33 (9.3%) were discharged, 38 (10.7%) did not follow up, and 12 (3.4%) had died.
* Computerized records were used to retrospectively calculate CED of imaging studies from 6 months before first contact with gastroenterology service until 6 months after most recent contact.
* Indications for gastrointestinal imaging included diagnosis of Crohn's disease, determination of extent of disease, and detection of complications.
* Abdominal CT examination was performed with oral and intravenous contrast and single-slice or 4-detector CT.
* Total diagnostic radiation exposure included nongastrointestinal imaging studies.
* 266 (75.1%) patients had at least 1 diagnostic imaging study.
* Mean number of studies per patient was 12.4 (95% CI, 10.5 - 14.3).
* Mean CED per patient was 36.1 mSv (95% CI, 30.8 - 41.4).
* Mean diagnostic radiation per patient per year of follow-up was 8.1 mSv (95% CI, 6.5 - 9.7).
* CT imaging consisted of 16.2% of imaging studies and 77.2% of all diagnostic radiation.
* In comparison of the first 5 years to the final 5 years of study:
o Mean number of imaging studies per patient increased from 5.6 (95% CI, 4.4 - 6.8) to 6.9 (95% CI, 5.8 - 8.0).
o Mean CED for patients who had imaging studies increased from 7.9 mSv (95% CI, 5.3 - 9.8 mSv) to 25.1 mSv (95% CI, 21.1 - 29.1 mSv).
o CT proportion of imaging studies increased from 5.2% to 19.7%.
o CT proportion of radiation exposure increased from 46.3% to 84.7%.
o Barium studies decreased from 15.7% to 10.2%.
* High cumulative exposure to diagnostic radiation, defined by a CED more than 75 mSv, occurred in 55 (15.5%) patients.
* Mean time from enrollment to high CED was 6.2 years (95% CI, 5.3 - 7.2 years).
* Mean age at time of high CED was 39.1 years (age range, 16.9 - 84 years).
* Factors associated with high CED:
o Diagnosis at age younger than 17 years (HR, 2.1; 95% CI, 1.1 - 4.1; P = .02)
o Upper gastrointestinal tract involvement (OR, 2.4; 95% CI, 1.2 - 4.9; P = .02)
o At least 1 course of oral steroids (OR, 3.8; 95% CI, 1.1 - 12.7; P < .01) or intravenous steroids (OR, 3.7; 95% CI, 2.0 - 6.6; P < .0001)
o Infliximab (OR, 2.3; 95% CI, 1.2 - 4.4; P = .02)
o First surgery during study period (OR, 3.6; 95% CI, 1.7 - 7.5; P < .001)
o More than 1 surgical procedure related to Crohn's disease (OR, 2.7; 95% CI, 1.4 - 5.4; P < .001)
o Penetrating disease (OR, 2.0; 95% CI, 1.0 - 3.9; P = .05)
* Factors associated with higher mean CED:
o Ileocolonic disease vs ileal or colonic disease alone (mean CED, 49 vs 27 mSv; P < .0001)
o Strictures or disease penetration vs nonstricturing, nonpenetrating disease behavior (mean CED, 18.3 vs 44.5 mSv; P < .0001)
o Immunosuppressive treatment with 6-mercaptopurine, azathioprine, or methotrexate (mean CED, 42.2 vs 29.5 mSv; P < .0001)
* Factors not related to high CED or higher mean CED were sex, smoking, family history of inflammatory bowel disease, diagnosis at study center, and age at referral.
* In 7 patients in whom malignant neoplasms developed, mean CED at time of cancer diagnosis was 29.9 mSv (range, 0 - 99.3 mSv), and only 1 patient had a high CED (> 75 mSv).
Pearls for Practice
* In patients with Crohn's disease, use of CT scans has increased with time. Mean CED is 36.1 mSv and is greater than 75 mSv in 15.5% of patients.
* In patients with Crohn's disease, risk factors linked to high CED of radiation are age younger than 17 years at time of diagnosis, upper gastrointestinal tract disease, steroid use, infliximab, multiple surgical procedures, and penetrating disease. Higher mean CED was linked with ileocolonic disease, stricture or penetrating disease, and immunosuppressive medication
