Examining Post Acute Care Relationships in an Integrated Hospital System. 2.2 Episode Construction


Study Period. The 2006 Medicare claims were the basis for the analysis. Although the analysis took place using the 2006 data, we also used data from the last quarter 2005 and first 6 months of 2007 to impose our episode construction criteria. Episodes begin with an index acute hospital admission following a 60-day period without acute, LTCH, IRF, SNF, or HHA service use. Episodes include all claims until a 60-day gap in LTCH, IRF, SNF, HHA, or outpatient therapy service use. By using both the 2005 and 2007 data, we limit any left-hand or right-hand truncation issues in analyzing the full 2006 claims file.9

Since the last post-acute prospective payment system was implemented in 2002, the data reflect full implementation of the post-acute prospective payment systems. Although the primary source of data analyses presented here is the 2006 Medicare claims, this study also compared findings to the previous ASPE study on 2005 PAC episodes (Gage, Morley, Constantine, et al., 2008).

Episode Definition. PAC episodes were based on live beneficiary discharges from an index hospitalization into one of the related care settings: IRF, LTCH, SNF, HHA, or hospital outpatient therapy.10 Hospital outpatient therapy services were included in the definition of PAC use because of the importance of these services among elderly beneficiaries in need of rehabilitation services. These services may be particularly important for beneficiaries requiring therapy services after illness or surgery, but not meeting the eligibility criteria for inpatient rehabilitation, skilled nursing or home health care.

Individual episodes were created at the beneficiary level. Each beneficiary's claims were sorted chronologically to construct a file of the PAC services. Identification of an index admission requires a 60-day period prior to the index acute hospital admission without an inpatient acute or post-acute (defined as LTCH, IRF, SNF, or HHA) claim. We used the following criteria to identify the start of a PAC episode of care:

Within 5 days of discharge from an acute hospital bed, first PAC admission to:

  • An IRF bed in either a freestanding IRF or a distinct part unit within acute hospital; or
  • An LTCH bed; or
  • An SNF bed; or

Within 14 days of discharge from an acute hospital bed, first PAC admission to:

  • An HHA; or
  • Hospital outpatient therapy service use.

PAC episodes are variable in length and include all claims subsequent to the first PAC service until a 60-day gap in use of inpatient acute, LTCH, IRF, SNF, HHA, or outpatient therapy services occurs. Acute hospital readmissions are included in the PAC episode. We used this variable length episode definition rather than a fixed length episode in order to capture longer periods of service use that may be related to an index acute hospital admission. Alternative episode definitions and specific methods for grouping claims to acute hospitalizations will be the focus of ongoing work in 2009.

Part B, Hospice, and Durable Medical Equipment Claims. In addition to the acute and PAC claims mentioned above, the 2006 episode files also included Part B (including physician services and therapy), hospice claims, and DME claims. These claims were included in the 2006 episode construction to provide a more comprehensive understanding of the resources associated with beneficiary care during PAC episodes. PAC episode start and end dates were determined based on acute and PAC claims as defined above. All Part B, hospice, and DME claims falling between the episode start and end dates were assigned to episodes of care. Part B therapy (physical therapy, occupational therapy, and speech therapy) claims were separated out from other Part B physician claims to better understand the use of both Part B therapy and hospital outpatient therapy services in episodes of PAC.

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