Heightened attention to imaging appropriateness and radiation exposure along with a sluggish economy and slashed reimbursements have slowed the growth of noninvasive imaging, from 4.1 percent between 1998 and 2005 to 1.4 percent between 2005 and 2008, according to a study published in the January issue of the American Journal of Roentgenology.

Amidst fears of radiation overexposure and inappropriate and overpriced imaging, and in addition to reports identifying imaging as the fastest growing physician service among Medicare beneficiaries, there "has been a variety of efforts in the last few years to rein in the cost of imaging, including such steps as the Deficit Reduction Act," explained David C. Levin, MD, of the Center for Research on Utilization of Imaging Services, at Thomas Jefferson University Hospital and Jefferson Medical College in Philadelphia, and colleagues. "More cuts may be forthcoming," continued Levin and co-authors.

As a result, the researchers investigated whether any change in the growth of imaging had occurred in recent years, examining the nationwide Medicare Part B Physician/ Supplier Procedure Summary Master Files for 1998 through 2008. These records included the more than 35 million beneficiaries enrolled in Medicare fee-for-service, while excluding the 10.3 million individuals enrolled in Medicare Advantage plans. The tests considered in this study were CT, MRI, nuclear medicine (including PET), echocardiography and other noncardiac ultrasound. Condition-mandated imaging, such as images taken for surgical procedures or radiation therapy, was excluded.

"There has been a dramatic change in the noninvasive diagnostic imaging growth trends in the Medicare fee-for-service population in recent years," with the 4.1 percent compound annual growth rate seen between 1998 and 2005 falling to 1.4 percent between 2005 and 2008, the authors observed. This trend translated to utilization rates (per 1,000 Medicare beneficiaries) of 3,190 in 1998, up to 4,230 in 2005 and 4,404 in 2008.

The compound annual growth rate of CT, averaging 10.1 percent between 1998 and 2005, fell to 5.1 percent between 2005 and 2008. For nuclear medicine, the 11 percent growth rate between 1998 and 2005 nearly flattened at 0.2 percent between 2005 and 2008. MRI growth likewise slowed, from 13.5 percent from 1998 to 2005 to 2.2 percent between 2005 and 2008. The latter two slowdowns are particularly important given public spending scrutiny, the authors said, since MRI and nuclear medicine represent the two most expensive imaging tests.

Similar trends were observed for ultrasound, with echocardiography falling from 7.4 percent to 2.7 percent and noncardiac ultrasound dropping from 5.0 to 2.9 percent, between 1998 and 2005 and 2005 through 2008, respectively.

Levin and colleagues also examined the growth rate of outpatient imaging, which is where "most discretionary use of noninvasive diagnostic imaging occurs." Growth in these facilities slowed substantially for all five modalities, though the rates for four out of five private office imaging modalities remained higher than in hospital outpatient facilities, with MRI being the only exception. "The slowdown in growth of outpatient advanced imaging ... is especially important, because the ambulatory settings (both private office and hospital outpatient facilities) are where most of the concern [over growth and spending] has been focused," Levin and colleagues wrote.

Although utilization growth slowed among both radiologists and nonradiologist physicians, the growth rate of the latter remained twice that of radiologists across the entire study. "These data refute the claims of some in other specialties that radiologists control imaging and are therefore responsible for the inappropriate growth in utilization," the authors argued. Nevertheless, Levin and colleagues did point out that cardiologists, highly criticized in past years for having fomented rapid growth, "deserve credit for having been able to limit the rapid growth that characterized nuclear cardiac imaging before 2005."

The authors attributed the declining growth rates to a number of factors, including the Deficit Reduction Act of 2005 reimbursement cuts, a decline in insurance coverage and affordability of imaging for many people due to the recession and growing attention to radiation exposure and imaging appropriateness. The authors concluded by expressing their "hope that by calling attention to these trends the concerns of the payors and policymakers may be somewhat allayed and, as a consequence, there will be less downward pressure on imaging reimbursements in the future."