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The use of nuclear myocardial perfusion imaging (MPI) declined substantially in a large integrated healthcare system during a recent 5-year period, researchers found.

Following an increase in use from 2000 to 2006 at Kaiser Permanente Northern California (KPNC), MPI use dropped by a relative 51% through 2011, from 1,748 to 855 tests per 100,000 person-years (P<0.001 for trend), according to , of Kaiser Permanente Medical Center in San Francisco, and colleagues.

Replacement by other imaging modalities -- including cardiac CT and stress echocardiography -- and a decline in coronary artery disease did not appear to explain the pullback from using MPI, the researchers reported in a research letter in the March 26 issue of the .

"The dramatic nature of the observed decline, which could not be explained by use of alternative modalities, is more consistent with changing provider behavior rather than a sudden decline in incident coronary artery disease," McNulty told 番茄社区 in an email. "The fact that we observed greater declines amongst lower-risk subsets (outpatients and younger persons) suggests MPI use became more discriminating (used preferentially in higher-risk persons)."

Another possible explanation, he said, "is the combination of sharing of utilization data across the many medical centers (leveraging a combined electronic medical record), recognition of variation in use, and finally, appropriate use becoming a defined quality initiative with education efforts."

The observed decline followed a boom in cardiac imaging from the 1990s through the middle part of the 2000s, of which MPI was a major part.

But, McNulty noted, "more recently, factors potentially discouraging use, such as appropriate use criteria, declining reimbursement, radiology benefits managers, and more publicized concerns about the health effects of radiation have emerged."

A recent study showed that MPI use declined in a Medicare fee-for-service population, and McNulty and colleagues set out to examine the issue across both younger and older patients treated within the KPNC system, which provides care for more than 2.3 million adults. The current analysis was restricted to patients 30 or older.

The decline in the use of MPI from 2006 to 2011 occurred in both sexes and did not vary based on history of percutaneous coronary intervention of CABG.

During the same time period, the use of stress echocardiography didn't change, and the use of cardiac CT increased, but only enough to offset about 5% of the overall decline in MPI if it was used as a direct substitute.

The rate of incident myocardial infarction -- used as a surrogate for coronary disease -- fell by a relative 27% during the period of declining MPI use (P<0.001).

There are no direct financial incentives to performing tests within the KPNC system, the authors noted, and thus, the results might not be applicable to other settings in which such incentives exist.

"Nevertheless," McNulty and colleagues wrote, "the substantial reduction in MPI use demonstrates the ability to reduce testing on a large scale with anticipated reductions in healthcare costs."

From the American Heart Association:

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