Dr. H. Gilbert Welch of Dartmouth College in Hanover, N.H., and colleagues examined patterns of repeat testing in a longitudinal study of a 5 percent random sample of Medicare beneficiaries.
They also studied the relationship between the proportion of the population tested and the proportion of tests repeated among those tested using the 50 largest metropolitan statistical areas as the unit of analysis.
"We examined repetitive testing for six commonly performed diagnostic tests in which repeat testing is not routinely anticipated," the study authors wrote. "Although we expected a certain fraction of examinations to be repeated, we were struck by the magnitude."
The study, published in the Archives of Internal Medicine, found among Medicare beneficiaries undergoing echocardiography, or examination of the heart, 55 percent had a second test within three years.
Repeat testing for the other examinations also was common: 44 percent of imaging stress tests were repeated within three years, as were 49 percent of pulmonary function tests, 46 percent of chest computed tomography, 41 percent of cystoscopies, an examination of the bladder, and 35 percent of upper endoscopies, examination of the digestive tract, the study said.
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