The initiating event for a PAC episode in our analysis is an index acute hospital stay in 2006. We define an index acute hospital stay as an acute hospital admission following a 60 day period without the use of acute, LTCH, IRF, SNF, or HHA services. Therefore, although all index acute hospitalizations took place in 2006, we also used data from the last quarter of 2005 to impose our episode construction criteria. The study sample was limited to live discharges from index acute hospitalizations. Beneficiaries were defined as PAC users based on discharge to SNFs, IRFs, or LTCHs within 5 days of discharge from the index acute hospitalization or discharge to HHAs or hospital outpatient therapy within 14 days of discharge from the index acute hospitalization. Our data file included 310,629 live index acute hospital discharges, and 109,236 of these beneficiaries were defined as PAC users (35.2 percent).