Regional variation in medicare imaging utilization and expenditures: 2007-2011 trends and comparison with other health services

Abstract

Purpose: A 2008 federal report expressed concern regarding substantial regional variation in imaging expenditures. The aims of this study were to evaluate trends in regional variation in Medicare imaging utilization and expenditures from 2007 to 2011 and to compare these trends with regional variation in other health service categories.

Methods: Data were based on CMS's Chronic Condition Data Warehouse and organized on the basis of 306 US health referral regions (HRRs). Imaging costs per beneficiary, standardized for regional differences in reimbursement rates, and imaging utilization per beneficiary were recorded per HRR from 2007 through 2011. Costs and utilization were also recorded for other service categories in 2011. Regional variation was assessed via relative risk (RR; the ratio between the highest and lowest HRRs) and coefficient of variation (CV; the standard deviation divided by the mean among all HRRs). Correlations between imaging and other service categories were assessed using Pearson's correlation coefficient.

Results: There was minimal change in regional variation in imaging costs or utilization between 2007 and 2011. Regional variation in imaging costs (RR, 5.70-5.88; CV, 33.0%-33.3%) was considerably greater than variation in imaging utilization (RR, 2.11%-2.25%; CV, 14.2%-14.6%). Imaging costs and utilization showed moderate to strong correlations with those of other service categories (r = 0.572-0.869). In 2011, regional variation in imaging utilization (RR, 2.25; CV, 14.2%) was considerably lower than variation in utilization of other service categories (RR, 2.80-10.78; CV, 20.9%-33.3%).

Conclusions: Regional variation in imaging utilization is considerably lower than both variation in imaging costs and variation in utilization of other major service categories. It is unclear whether variation in imaging utilization provides an optimal individual target for major policy decisions.

Keywords: Medicare; diagnostic imaging utilization; health policy; radiologists.