High costs of CT screening

Whole-body computed tomography (CT) screening has become popular despite the typical $1,000 price tag for the comprehensive X-ray scan. There can also be a hidden cost for each scan, of between $1,100 and $3,500, borne by the U.S. health care system, according to a new study. The extra expense results from the high number of harmless anomalies, or false positives, that scans turn up and that doctors must then check out (SN: 9/20/03, p. 184: To Your Health?).

Radiologist G. Scott Gazelle and his collaborators at the Massachusetts General Hospital in Boston used a computer to model 500,000 pairs of people from 45 to 55 years old. In the model, one person in each pair underwent CT screening, and the other relied on doctors for diagnosis and care of disorders such as coronary artery disease, abdominal aortic aneurysms, and cancers of the ovaries, pancreas, lung, liver, kidney, or colon.

The model estimated how much sooner CT scans would find such disease and any difference in life expectancy that would result from the earlier diagnosis.

The results suggest that for 50-year-old men, CT scanning would accelerate diagnosis in 2 percent of individuals, but that a stunning 90.8 percent of the men would have at least one false positive in their scan. Among this age group, scanning would yield an average life expectancy gain of only about 6 days, compared with conventional care. Yet subsequent tests would cost the health care system an extra $2,500 per person. The economic impact of the scans would be even greater for younger, and generally healthier, groups, the researchers report in the February Radiology.

Gazelle concludes that CT screening for asymptomatic disease is “causing a drain on the health care system.”

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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