Nationwide trends in rates of utilization of noninvasive diagnostic imaging among the Medicare population between 1993 and 1999.

PURPOSE

To determine current utilization rates and recent nationwide trends for noninvasive diagnostic imaging (NDI) among the Medicare population.

MATERIALS AND METHODS

Medicare Part B claims data files from 1993, 1996, and 1999 were analyzed for all procedure codes related to NDI. NDI codes were grouped into 22 imaging categories, as well as seven imaging modality groups. The data were analyzed to determine the overall nationwide utilization and relative value unit (RVU) volume and rates and changes in utilization rates and RVU rates between 1993 and 1999 for the Medicare fee-for-service population, which included approximately 33 million enrollees per year.

RESULTS

The overall utilization rate for all NDI in 1999 was 324,974 examinations per 100,000 enrollees. Conventional radiography was the most utilized imaging technology (55.5%), followed by ultrasonography (US) (20.5%), computed tomography (CT) (8.8%), mammography (6.0%), nuclear imaging (5.2%), magnetic resonance (MR) imaging (2.6%), and bone densitometry (1.5%) (percentages do not add up to 100% due to rounding). In the 6-year interval from 1993 to 1999, the rate of NDI utilization increased 3.8%. The utilization rate for conventional radiography decreased 13.7%, while that of all other modalities increased a combined total of 39.1%. During this 6-year period, RVU rates per 100,000 increased 14.6%, with RVUs for MR imaging increasing 76.6%; those for nuclear imaging, 38.7%; those for CT, 28.3%; and those for US, 24.2%.

CONCLUSION

A 3.8% increase in the rate of NDI utilization occurred during the 6-year period between 1993 and 1999. A considerably larger increase in RVU rates (14.6%) occurred during the same time period.