The Effect of Utilization Regulation: The Case of CT Scans and the Affordable Care Act
We develop a model describing both hospital and physician behavior in response to this regulation where hospitals voluntarily comply to reduce imaging associated with the IEMs in expectation of future penalties but have varying capacities to influence physician behavior. Using this framework, we then test whether the IEM was associated with reductions in imaging by focusing on IEM OP-14 which reports rates of same day brain and sinus computed tomography (CT). Using Medicare claims data from 2008-2013, we examine the likelihood that a patient receiving a brain CT also received a sinus CT on the same day is associated with the reported OP-14 measure at the patient’s facility. We employ a logistic difference-in-difference regression model that exploits same day brain and sinus CT imaging orders outside of hospital care settings, and thus not reported as a part of IEM OP-14, as a control group and adjusting for confounders such as patient characteristics, patient risk, ordering physician, and geographic variation in care.
Preliminary results indicate that IEM OP-14 was associated with a small but significant reduction in same day brain and sinus CT orders, with the likelihood of a same day brain and sinus CT being ordered falling by 2 percent to 5 percent, and on average reducing utilization by 3.8 percent across all model specifications. However, a significant increase in utilization associated with passage of the ACA offset the effect of IEM OP-14 in most model specifications. These preliminary results were qualitatively similar after testing other model specifications such as controlling for same day brain and sinus CTs in hospital emergency departments, which are responsible for much of the growth in CT utilization over time.