To learn more about the use patterns of beneficiaries over longer periods of time, ASPE and RTI examined patterns of acute and PAC use for beneficiaries with an initiating event (acute, LTCH, IRF, or HHA) in 2006 and followed these beneficiaries using 2 years of claims data. RTI constructed twenty-four 30-day windows over which to look at service use. Similar to the prorated episode definition described above, claims were prorated so that only days and dollars associated with the portion of the claim in each of the 30-day windows were attributed to the window. As in creating the prorated episode definition, only dollars associated with visits and days in each of the windows were assigned to the windows, and prorated payments per window were estimated by dividing the total claim Medicare payment amount by the total number of visits (or days in the case of institutional claims) on the claim and assigning payments based on those that occurred in each window. Analyses of this sample included examination of the percentage of beneficiaries with a claim, mean total acute and PAC payments, and mean payments per service type. Analyses were conducted by type of initiating event and also included some MS-DRG specific analyses to learn more about how patterns change for beneficiaries with different types of diagnoses.