Recent payment and utilization trends in radionuclide myocardial perfusion imaging: comparison between self-referral and referral to radiologists

The aim of this study was to examine the effects of self-referral by comparing recent trends in payments and utilization rates for radionuclide myocardial perfusion imaging (MPI) among radiologists and cardiologists between 1998 and 2006.

Nationwide Medicare Part B claims databases for 1998 through 2006 were used. The 4 primary MPI codes were selected. Using Medicare's physician specialty codes, physician providers were identified as radiologists, cardiologists, or other physicians. Payments for MPI to the 3 groups were tracked over the study period. Trends in utilization rates in both hospital and private office settings were also compared among the 3 groups. In addition, utilization trends were studied for related procedures, such as stress echocardiography (SE) and invasive diagnostic coronary angiography (CA).

Between 1998 and 2006, Medicare Part B payments to radiologists for MPI increased from $72.6 million to $84.0 million (+16%), while among cardiologists, payments increased from $242.6 million to $972.0 million (+301%). Private office utilization rates per 1,000 Medicare beneficiaries increased by 215% among cardiologists, compared with 32% among radiologists. In hospital settings, the rate changes were much more modest. Hospital utilization rates were consistently higher among radiologists than cardiologists; in hospital settings in 2006, the rate was 15.3 per 1,000 among radiologists, compared with 11.8 per 1,000 among cardiologists. Between 1998 and 2006, the utilization rate for SE among cardiologists increased by 20%, and the rate for diagnostic CA among cardiologists also increased by 20%.

In recent years, there have been very sharp increases in the costs and utilization of MPI among cardiologists compared with radiologists. Most of the growth occurred in cardiologists' private offices. In hospital settings, radiologists still do more MPI examinations than cardiologists. Because MPI is a highly reimbursed procedure and there is no evidence that coronary disease is increasing in frequency in the Medicare population, this trend raises a concern about inappropriate self-referral. This is particularly true in view of the facts that the utilization of a competing procedure such as SE also continues to increase among cardiologists and that MPI is not substituting for an invasive procedure such as diagnostic CA.