AJR: ED patients knowledge of CT rad risk varies

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Most, but not all, emergency department (ED) patients referred to CT imaging prioritize diagnostic accuracy over radiation risks. However, patient knowledge about radiation risks varied and targeted education may benefit ED patients, according to a study published in the November edition of the American Journal of Roentgenology.

Although use of CT imaging has increased in EDs in the last decade, few studies have assessed patient knowledge and attitudes about radiation. Kevin M. Takakuwa, MD, of the department of emergency medicine at Thomas Jefferson University Hospital in Philadelphia, and colleagues conducted a prospective survey study to assess knowledge and attitudes about radiation from CT and potentially identify specific populations who might benefit from education.

The study population consisted of 383 patients for whom CT was ordered from June 23, 2008 to July 31, 2008 at an urban academic medical campus. Research assistants administered a six-question survey and collected information about age, sex, race, education, insurance type and body mass index.

“Overall, 79 percent and 83 percent of patients estimated the risk of cancer from chest radiography and CT, respectively, as none, very small or small,” according to Takakuwa and colleagues. However, only seven percent accurately believed that a CT gave significantly greater amounts of radiation than chest radiography, added the researchers. Twenty-five percent of patients thought CT gave less radiation than chest radiography, and 41 percent believed radiation for the two studies was equivalent.

When patients were stratified into groups, whites, patients with more education, those with lower pain scores and those with private insurance and no insurance were significantly more likely to believe the risk of cancer from a single CT study was small compared with blacks, patients with less education, patients with higher pain scores and those with Medicaid, Medicare or other government insurance, continued Takakuwa and colleagues.

Researchers identified several additional misperceptions. Sixty-seven percent of patients who thought that radiation from CT was greater than chest radiography also though the risk of cancer from the two studies was equivalent, and only 31 percent of patients associated less radiation with lower cancer risk, according to researchers.

While 74 percent of patients agreed or strongly agreed that it is more important for physicians to use CT for diagnosis than to worry about radiation, patients with Medicaid, Medicare or other government insurance were more likely to disagree that diagnosis of the acute problem was more important than worrying about CT radiation, researchers explained. The authors conjectured that this group may have been more concerned about radiation because they were less likely to understand the risk of cancer from a single CT study was small.

African-American patients and those with lower pain scores were more likely to agree that it was important for physicians to take the time to discuss the risks and benefits of a test than to use judgment to order the best diagnostic test, continued Takakuwa and colleagues.

The researchers acknowledged that survey studies are associated with reliability, validity and reproducibility problems, and that the small study may not be generalizable to other populations. However, they did find statistical significance for many responses.

“Our results suggest that we may help ED patients better with targeted teaching about radiation, decreasing their pain, discussing risks and benefits and asking them to participate in the ordering of their diagnostic tests,” summed the authors.