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National Healthcare Disparities Report, 2005

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Home Health Outcome and Assessment Information Set (OASIS)


U.S. Department of Health and Human Services, Centers for Medicare & Medicaid Services (CMS).

Description/Primary Content

The OASIS is a group of data elements that represent core items of a comprehensive assessment for an adult home care patient. Because OASIS can measure changes in a patient's health status between two or more time points, it forms the basis for measuring patient outcomes for purposes of outcome-based quality improvement (OBQI).

The general categories of data and health status items in OASIS include demographics and patient history, living arrangements, supportive assistance, sensory status, integumentary (skin) status, respiratory status, elimination status, neuro/emotional/behavioral status, activities of daily living, medications, equipment management, and information collected at inpatient facility admission or agency discharge.

Demographic Data

Gender, age, race/ethnicity, State of residence, marital status, informal caregiver assistance, living arrangement, current payment sources for home care and health status.

Population Targeted

U.S. adult, nonmaternity, home care patients receiving skilled services.

Mode of Administration

Completed by home health agency (HHA) personnel.

Years Collected

Medicare and Medicaid certified agencies have been required to collect data since 1999.

Data Collection Schedule

Most OASIS data items are designed to be collected at the start of care and every two months thereafter until and including time of discharge.

HHAs are required to electronically transmit OASIS data only for home care patients receiving Medicare and Medicaid skilled services to State survey and certification agencies. The State agencies have the overall responsibility for collecting OASIS data in accordance with CMS specifications. The State is also responsible for preparing OASIS data for retrieval by a national repository established by CMS.

Geographic Estimates

National, State, agency.

Contact Information

Agency homepage:

Data system homepage:


The Home Health Care tables are based on OASIS assessment data from January 1-December 31 in each year. The data for the measures are based only on home health episodes that began and ended in the same calendar year. Approximately 22 percent of patients have more than one episode in the same year.

Risk Adjustment for Measures: Each State average rate is risk adjusted using logistic regression models (details at The national rate is the observed rate because the national rate is already reflective of national characteristics.

For OASIS improvement measures, a person is not included if he or she is at the highest level and cannot improve any more. Similarly, a person is excluded from stabilization measures if he or she is at the lowest level and cannot decline any more. Consequently, the denominator for each of the measures can vary widely because of these definitions. On average, for example, only 30 percent of all episodes are included in the urinary incontinence measure and about 40 percent for the confusion frequency measure, while 95 percent of episodes are included in bathing stabilization and about 83 percent of episodes for ambulation improvement.



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