Study Describes Rise and Fall of Nuclear Cardiac Imaging Test

Marlene Busko

March 25, 2014

SAN FRANCISCO, CA — A new study provides a glimpse of the shift over the past decade in the number of requests for nuclear myocardial perfusion imaging (MPI) tests to determine areas of the heart with decreased blood flow. The study was published as a research letter in the March 26, 2014 issue of the Journal of the American Medical Association[1].

Among members of the Kaiser Permanente healthcare plan in Northern California, the number of nuclear MPI tests performed first rose by 41% from 2000 to 2006, then dropped by 51% from 2006 to 2011. During the latter period, physicians were not ordering more alternative imaging tests.

The sharp drop in MPI tests occurred after the publication of appropriateness criteria for single-photon-emission computed-tomography (SPECT) MPI in 2005[2]. "Although the abrupt nature of the decline suggests changing physician behavior played a major role, incident coronary disease, as assessed by MI, also declined" by 27%, the researchers, led by author Dr Edward J McNulty (Kaiser Permanente Medical Center, San Francisco, California), note.

"The observed decline occurred in the context of a healthcare-delivery system without direct financial incentives to perform tests," McNulty and colleagues write. "Nevertheless, the substantial reduction in MPI use demonstrates the ability to reduce testing on a large scale with anticipated reductions in healthcare costs."

Trends in Cardiac Imaging

Nuclear MPI tests accounted for much of the rapid growth in cardiac imaging that occurred from the 1990s through the mid-2000s, the researchers explain. However, a recent study showed that following the new appropriate-use criteria and changes in reimbursement, physicians are ordering somewhat fewer MPI tests for individuals covered by Medicare.

To examine trends in the use of MPI in a younger population, they analyzed data from 2000 to 2011 from individuals aged 30 and older who were covered by the Kaiser Permanente Northern California healthcare plan, which provides inpatient and outpatient care for more than 2.3 million adults.

During this time, 302 506 patients at 19 facilities had an MPI test.

From 2000 to 2006 to 2011, the annual rate of nuclear MPI tests went from 1239 to 1748 to 855 per 100 000 person-years.

From 2006 to 2011, the number of MPI tests dropped by 58% among outpatients vs 31% among inpatients, and it declined by 56% in people younger than 65 vs 47% in older individuals. The decline was similar in men and women and individuals who did or did not receive PCI or CABG.

From 2007 to 2011, cardiac computed tomography increased slightly, and this test may have replaced 5% of the MPI tests, the authors suggest. The number of stress echocardiography tests was unchanged, and hardly any perfusion positron-emission tomography and perfusion MRI tests were performed.

The study was supported by a grant from the Kaiser Permanente Northern California Community Benefits Program. McNulty had no conflicts of interest; disclosures for the authors are listed in the article.


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