Duke 2008 | ASHE | Equity and Efficiency in Health and Healthcare

Introduction and Background: Imaging technology provides a useful case for studying the challenges that stem from advancing technologies. While the costs of persistently growing imaging use are increasingly apparent, and worries about overuse are common, there may also be important offsetting benefits. Making sensible public policy requires attention to a number of ways in which adoption of new technologies impacts social welfare. This paper outlines important issues that arise when evaluating the welfare effects of technology adoption decisions, and presents new empirical evidence about the value of new imaging adoption. Data and Methods: We focus on CT and MRI angiography (CTA and MRA), diagnostic imaging procedures that can be used to examine circulation problems, such as artery blockages or aneurysms. These have important advantages for our purposes. They are used to diagnose conditions that can have serious observable health implications. They can also replace other observable procedures that are invasive and can cause serious side-effects. We can thus examine whether expanding imaging availability, as it drives the use of CTA and MRA, is associated with identifiable benefits for specific types of patients or whether, for example, expansion leads to higher rates of diagnostic testing without (observable) benefits. We can also address populationlevel questions, including the ways that imaging availability affects patterns of diagnostic testing in the overall beneficiary population. We do these analyses using Medicare claims data to track use of CTA, MRA, related invasive diagnostic tests, follow-up tests and therapeutic procedures, and relevant health outcomes among a 20% sample of Medicare FFS patients over the period 1998-2005. We use these data to produce both individual-level and Health Referral Region level measures of procedure use and outcomes. We use a series of regression analyses to analyze relationships: (1) whether growth in CT and MRI availability are associated with changes in the probability with which patients deemed at risk for stroke or aneurysm receive any diagnostic testing, more invasive testing, or (less invasive) CTA/MRA; (2) whether changes in the availability of services affect the probability of receiving testing even in patients without prior indication of risk; (3) whether diagnostic testing is associated with follow-up procedure use at the level of the individual patient or area population; and (4) whether there are changes in rates of adverse outcomes, either at the individual patient or area population levels. Results: Results thus far suggest that expanding imaging use reduces the use of more invasive substitute tests, which seems likely to be good for patients. Results also suggest that more imaging availability also greatly expands the number of people being tested, even among those without prior strong indication of risk, and does not produce clear improvements in average population health outcomes. Work is ongoing to refine and extend these results. Discussion and Conclusion: In the cases we study, we find evidence suggesting concern about the extent to which we are achieving optimal levels of imaging adoption from a social perspective. We discuss reasons for this, and possible interpretation of these findings for policy implementation.