Handling incidental findings: the (less than) 1% solution

Pathologies such as infections, or even tumors, crop up from time to time in patients examined for entirely unrelated issues. These "incidental findings"can put doctors-and patients-in a tight spot. How do they proceed with the patient, knowing that many of the asymptomatic signs of disease may never lead to clinical problems, or may simply be false positives?

For those who have run into this situation and chosen the path of less intervention, there is now research evidence that they likely did the right thing.

Researchers at the Mayo Clinic in Rochester, Minn., noted that although incidental findings, such as a tumor or infection, are uncovered on radiological exams in up to 40% of research participants, an expert panel determined that clinical action was justified in only 6.2% of the cases. And, of those who received treatment, only a miniscule number actually benefited.

Lead author Nicholas M. Orme, MD, a resident in the department of general internal medicine, and colleagues documented incidental findings in 567 of 1,426 subjects participating in research during January through March 2004. Each image was interpreted by a radiologist the day it was performed. Just 35 of these 567 subjects ultimately received medical treatment for the incidental finding during a three-year follow-up period. Only six of these 35, less than 1% of all subjects with incidental findings, gained any clear medical benefit from the intervention. Three of the 35 carried a "medical burden"as a result (Arch Intern Med 170:1525-1532, 2010).

The incidental findings noted in the paper were most often found on CT scans of the abdomen and pelvis, followed by CT of the chest and MRI of the head. The risk of an incidental finding was determined to increase with age. Incidental findings, the authors said, raise the potential for early diagnosis of asymptomatic life-threatening disease, but also invite costly, invasive, and ultimately unnecessary interventions for benign processes.

In an accompanying editorial, Bernard Lo, MD, offered ethical guidelines for addressing incidental findings. His recommendations included making a distinction between the responsibilities of the research and those of the treating physician. Dr. Lo is from the Program in Medical Ethics at the University of California, San Francisco.

"A researcher’s regulatory obligations to participants are to obtain informed consent and minimize harms caused by research interventions, "Dr. Lo wrote. "The researcher is not required to minimize harms to the participant by detecting previously undiagnosed conditions that are beyond the scope of the study. However, the researcher has an ethical obligation to exercise reasonable care in identifying incidental findings"(Arch Intern Med 170:1522-1524, 2010).

Dr. Lo also outlined specific actions for responding to incidental findings in research studies, urging researchers to ask and answer the following questions, such as "Who will read the imaging results?"and "If an incidental finding is recognized, how will its significance be assessed?"

"The possibility of incidental findings, and their ramifications, should be part of the informed consent process, "Dr. Lo said. "The work by [Dr. Orme’s group] helps us start to quantify their impact."