“…Created by the Dartmouth Institute for Health Policy and Clinical Practice (2014), Hospital Service Areas (HSAs) and Hospital Referral Regions (HRRs) have been increasingly used as analysis units in policy studies including the recent IOM (2013) report on healthcare spending. The HSAs are an area where most of local hospitalization occurs (Klauss, Staub, Widmer, & Busato, 2005). The HRRs are an aggregated level based on the HSAs, wherein patients are referred for major cardiovascular surgical procedures and for neurosurgery (Center for Evaluative Clinical Sciences, 1999).…”