Study: Rising rad dose among patients with gastrointestinal woes spurs call for guidelines
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The authors called for the development of evidence-based guidelines for image analysis among this population. Alan N. Desmond, MB, from the departments of gastroenterology and radiology at Cork University Hospital in Cork, Ireland, and colleagues designed the retrospective study with three objectives: to examine diagnostic imaging in patients referred to a specialized gastroenterology center; to estimate the cumulative effective dose (CED) of radiation received by patients with inflammatory bowel disease (IBD), other organic gastrointestinal (GI) disorders and functional GI disorders and to identify risk factors for increased risk of CED.
The study population was comprised of 2,509 patients referred to the gastroenterology clinic at a tertiary center specializing in IBD and functional GI disorders from January 1, 1999, to January 1, 2009, and who underwent at least four weeks of follow-up.
A total of 38.1 percent of patients had IBD, 40.6 percent had non-IBD organic GI disorders, 25.1 percent had functional GI disorders and 6.5 percent were not diagnosed with a disorder. More than one diagnosis was made in 10.3 percent of patients.
The cohort included 1,066 men and 1,443 women, with a mean age at referral of 39.8 years (range, 1.5-87.0 years).
Desmond and colleagues reported that 57 percent of patients underwent diagnostic imaging and a mean number of four studies per patient were performed.
Factors associated with an increased likelihood of imaging included older age at referral and patients with a longer duration of follow-up as well as diagnoses of IBD, functional gastroduodenal disorders, functional bowel disorders and functional disorders of childhood and adolescence.
The researchers found increased use of imaging during the course of the study. CT studies increased from 10 studies per 100 patients in 1999-2000 to 18.6 in 2008-2009. Mean annual radiation exposure increased from 2.2 mSv in 1999-2000 to 3.1 mSv in 2008-2009. Mean cumulative radiation exposure per patient was 10.4 mSv.
According to Desmond and colleagues, the 90th percentile for total radiation exposure was 30.8 mSv. “The most concerning finding might be that more than half of patients with cumulative exposure exceeding the 90th percentile were younger than 35 years old at last clinical contact,” they wrote, adding that the lifetime excess relative risk of malignancies in this subgroup would be between 1 and 8.6 percent for men and 1.8 and 14.8 percent for women.
The clinical benefits of diagnostic imaging in disorders of the GI tracts, particularly Crohn’s disease, are clear, according to the researchers. However, they noted that the benefits among patients with functional GI disorders are less clear. Specifically, “systematic reviews have emphasized the low diagnostic yield of [imaging in patients with symptoms entirely consistent with a functional diagnosis].”
They pointed to a positive note among this group, which tends to be female and of reproductive age. Patients with functional disorders were exposed to significantly less radiation than those with IBD and other organic disorders.
The researchers noted downsides of alternate modalities. Ultrasound can be time-consuming and operator-dependent, while capsule endoscopy is a second-line modality that is not universally available. MRI is associated with cost and availability issues.
“Given the likely deleterious effects of exposure to ionizing radiation and the age and gender profile of patients in these disease categories, there is a clear need for evidence-based guidelines on the use of diagnostic imaging in patients with organic and functional GI disorders,” concluded Desmond and colleagues.