In 2014, medical imaging was involved in three of four common diagnostic procedures deemed by the literature to present more risk of harm and/or unjustifiable expense than warranted by potential benefit, according to a special report published Nov. 9 in JAMA Internal Medicine.

The three were screening for asymptomatic carotid stenosis, screening for diagnostic thyroid cancer—both of which widely use ultrasonography—and head CT.

Daniel Morgan, MD, MS, of the University of Maryland and colleagues conducted a structured review of 10 such articles published in NIH’s PubMed last year.

They grouped the 10 articles into three categories—overdiagnosis, overtreatment and methods to avoid overuse.

Their conclusions on the three offending imaging-oriented diagnostic procedures:

• There is no benefit to screening for asymptomatic carotid stenosis;
• Head CT is often ordered but rarely helpful; and
• Thyroid cancer is massively overdiagnosed, leading to concrete harms.

Homing in on the head CT finding, the authors looked at a retrospective cohort analysis reviewing 130 patients admitted for any cause at least seven times during a one-year period to a tertiary care center.

Patients received a mean of almost seven CT scans, including three head CT scans. More than one-third (36 percent) of head CTs were ordered to evaluate for altered mental status. Only 4 percent (7 of 127) of head CTs had clinically significant findings that resulted in a change in management.

“This imaging can also reveal unimportant, incidental findings that lead to overdiagnosis and overtreatment,” they write. “A second head CT scan rarely affects patient management.”

Looking at an analysis of population-based thyroid cancer screening in South Korea, the authors noted that overdiagnosis of the disease there is “extremely common” and often leads to overtreatment bringing on such harms as hypoparathyroidism and paralysis of the vocal cords.

As for screening for asymptomatic carotid stenosis, they point to a systematic review and meta-analysis by the U.S. Preventive Services Task Force demonstrating that no studies provided data on whether screening for carotid stenosis reduced stroke.

They add that, with a specificity of 92 percent, carotid duplex ultrasonography screening leads to many more false than true positives—and is supported by no evidence of concomitant stroke reduction.

In describing methods to avoid overuse, Morgan et al. mention no imaging modalities or procedures by name but broadly urge physicians to “be cautious in using diagnostic tests to identify disease without high pretest probability, because most disease can be diagnosed with a thoughtful history and skillful physical examination.”

The authors explain their review of the literature on medical overuse, which follows their review of 2013 literature published last January, by pointing out that published literature documenting overuse “may benefit patients and populations if it stimulates decisions to avoid overused diagnostics and therapeutics.”

Noting the difficulty of breaking habits around the ordering of commonly used tests and treatments, they urge “thoughtful questioning” of many current practices that “seem logical but are without evidence” and ought to be reconsidered in order to produce “a less dogmatic and more patient-centered approach to care.”