Impact of the American Tax Payer Relief Act on stereotactic radiosurgery utilization in the United States.

ATRA implementation in 2013 caused an initial spike in Gamma Knife SRS utilization, followed by a decline to rates similar to the years before implementation. These findings indicate that the ATRA provision mandating Medicare reduction of outpatient payment rates for Gamma Knife to be equivalent with those of LINAC SRS had a significant short-term impact on the radiosurgical treatment of metastatic brain disease throughout the US, serving as a reminder of the importance/impact of public policy on treatment modality utilization by physicians and hospitals.