CT Risks Rarely Discussed Before Testing

Troy Brown

March 04, 2013

Approximately 1 in 3 imaging tests in the United States are performed in situations in which clinical benefit is unlikely to outweigh risks, yet few clinicians discuss these risks with patients undergoing tests, and even when they do, patients' knowledge about the risks does not change substantially, according to a research letter published online March 4 in JAMA Internal Medicine.

Tanner J. Caverly, MD, an instructor of medicine and a primary care research fellow in the Division of General Internal Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, and colleagues conducted a survey of 286 consecutive individuals undergoing outpatient computed tomography (CT) at Denver Veterans Affairs Medical Center from November through December 2011. They examined the frequency of risk communication discussions that occurred before patients underwent CT and how those discussions informed patients about potential harms related to scanning.

A total of 271 individuals (94.8%) completed the survey. Most (92%) had undergone 1 or more previous scans, and 38% reported having more than 5 previous scans. Many respondents (62%) believed the physician was the primary decision-maker regarding whether the patient underwent CT.

Slightly more than one third (35%) of respondents reported that they had discussed the potential risks of CT with their healthcare provider. Fewer still (17%; n = 46) said they had done all of the following with their provider before undergoing the CT scan: shared the final decision, discussed the potential benefits, and discussed the potential risks.

"Because the risk of developing cancer from the radiation associated with a single CT scan has led to calls for mandatory informed consent, we asked specific questions about radiation," the authors write.

About one third (37%) of respondents knew that CT involved more radiation than chest X-ray, but patients who discussed risks and benefits with their physician were no more likely to know this information than patients who did not discuss risks and benefits with their physician (P = .60). This result was unchanged in multivariate analysis after adjusting for age, education, sex, number of previous scans, and ordering clinician.

None of the respondents identified incidental findings as a potential risk of CT.

"Correcting the lack of knowledge and the lack of communication about the potential harms of imaging tests—thereby enhancing shared decision making—should be part of any attempt to curb imaging overuse," the authors write. "It is time to begin empirically testing risk communication methods and translate these methods into routine clinical practice," the authors conclude.

Dr. Caverly is supported by an institutional grant from the National Research Service Award, and 2 coauthors were supported in part from a Health Resources and Services Administration grant to the University of Colorado Preventive Medicine Residency Program. One coauthor was supported in part by a Physician Training Award in Preventive Medicine from the American Cancer Society. The authors have disclosed no other relevant financial relationships.

JAMA Intern Med. Published online March 4, 2013.

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