Do Imaging Studies Performed in Physician Offices Increase Downstream Utilization?: An Empiric Analysis of Cardiac Stress Testing With Imaging
Is subsequent testing affected by whether stress testing with imaging is performed at a physician office versus at a hospital-outpatient facility?
A total of 82,178 adults with private health insurance from 2005 to 2007 who underwent ambulatory myocardial perfusion imaging (MPI) or stress echocardiography (SE) were identified. Subsequent MPI, SE, cardiac catheterization, or revascularization within 6 months was compared between patients in whom stress testing was initially performed in a physician office versus in a hospital outpatient setting.
Overall, 85.1% of MPI and 84.9% of SE were performed in physician offices. The proportion of patients who underwent subsequent MPI, SE, or cardiac catheterization was not statistically different between physician office and hospital outpatient settings for MPI (14.2% vs. 13.9%, p = 0.44) or SE (7.9% vs. 8.6%, p = 0.21). However, patients with physician office imaging had slightly higher rates of repeat MPI within 6 months compared with hospital-outpatient imaging for both index MPI (3.5% vs. 2.0%, p < 0.001) and SE (3.4% vs. 2.1%, p < 0.001), and slightly lower rates of cardiac catheterization after index MPI (11.4% vs. 12.2%, p = 0.04) and SE (4.5% vs. 7.0%, p < 0.001). Differences in 6-month utilization were observed across the five health care markets after index MPI, but not after index SE.
Physician office imaging is associated with slightly higher repeat MPI and fewer cardiac catheterizations than hospital outpatient imaging, but no overall difference in the proportion of patients undergoing additional further testing or procedures. Although regional variation exists, especially for MPI, the relationship between physician office location of stress testing with imaging and greater downstream resource utilization appears modest.
Previous studies have implied that tests performed in a physician’s office are a major contributor to the growth of noninvasive imaging. This study found slightly higher rates of repeat noninvasive imaging tests after initial office-based testing, but slightly lower rates of revascularization procedures. The authors offer possible explanations including the convenience of repeat office testing rather than outside-of-office referral for catheterization, variability of study quality, or imaging artifacts with the ability to personally view and discount as artifact equivocal abnormalities on office testing, differences between laboratories in thresholds for abnormal tests, and financial incentives for repeat office stress testing. Without knowing how many tests (initial or follow-up) were justified and the accuracy of the interpretations, both explanation and implications (clinical and financial) remain conjectural.
Keywords: Myocardial Perfusion Imaging, Physicians' Offices, Follow-Up Studies, Echocardiography, Stress, Cardiology, Cardiac Catheterization, Catheterization, Thiazolidinediones
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