Outcome and Assessment Information Set (OASIS)

The Outcome and Assessment Information Set (OASIS) is a set of data items designed to enable the systematic rigorous measurement of home health care patient outcomes. The data set was developed during the 1990s by a University of Colorado research team funded by the Centers for Medicare and Medicaid Services (CMS), the New York State Department of Health, and the Robert Wood Johnson Foundation. National panels of clinicians, administrators, and researchers participated in item selection, and extensive empirical testing was conducted. In 1999, the CMS mandated the collection of OASIS data by all Medicare-certified home health agencies for adult (age 18 years and older) nonmaternity Medicare and Medicaid patients. Selected items from the OASIS were incorporated into the home health resource groups (HHRGs) for the prospective payment system for home care in October 2000.

OASIS data are collected at the start of each home health episode, at every 60 days thereafter, and at the end of the episode (defined as discharge or admission to an inpatient facility). The OASIS items were designed to be integrated into an agency's routine patient assessment. The start-of-care OASIS contains 71 items covering demographics and patient history (13 items), living arrangements (2 items), supportive assistance (4 items), sensory status (5 items), integumentary status (13 items), respiratory status (2 items), elimination status (5 items), neurological/ emotional/behavioral status (7 items), functional status (activities of daily living [ADLs] and instrumental activities of daily living [IADLs], 14 items), medication (3 items), equipment management (2 items), and therapy need (1 item).

The primary purpose of OASIS data collection is to measure patient outcomes, which are central to home health agency efforts to improve quality. An outcome is defined as a change in a patient attribute (e.g., ambulation/locomotion) between two points in time, specifically the beginning and the end of a patient's episode. OASIS data currently are used to derive three [Page 445]types of outcome measures: improvement outcomes, stabilization outcomes, and utilization outcomes. A patient improves when the scale value for the OASIS item shows that the patient is less dependent at discharge than at start of care (i.e., the scale value at discharge is lower). If the patient is at the most independent or “healthiest” extreme of the scale at the start of care (e.g., a value of 0 for the ambulation/locomotion item), it is impossible to improve and therefore the measure is not defined for the patient. When aggregated to the agency level, “improved in ambulation/ locomotion” is the percentage of a home health care agency's patients who improve in ambulation/ locomotion based on the start of care and discharge OASIS data.

Stabilization outcomes are similar to improvement outcomes but measure “nonworsening”; that is, the patient's condition either improves or stays the same. Stabilization occurs when the patient's discharge OASIS item is at the same scale value as, or at a lower scale value than, the scale value at the start of care. (Because stabilization measures nonworsening, patients at the most dependent scale value at the start of care cannot worsen and therefore are excluded.) Utilization outcomes are measures that serve as proxy indicators of a patient's health status. The three utilization outcomes currently obtained from OASIS data are acute care hospitalization, discharge from home health care to the community, and emergent care.

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