Since 1999, the Centers for Medicare and Medicaid Services has collected and reported data from home health agencies through the Home Health Outcome and Assessment Information Set (OASIS). Data is obtained from all adult patients at Medicare and Medicaid-certified home care agencies with few exclusions (patients under the age of 18, patients receiving maternity services, and patients receiving only chore or housekeeping services). It is collected as a means to enable the rigorous and systematic measurement of patient home health care outcomes with appropriate adjustment for patient risk factors affecting those outcomes.

OASIS data elements include the socio-demographic, environmental, support system, health status, and functional status attributes of adult Medicare and Medicaid patients. Data is collected at the start of care, 60-day follow-ups, and discharge.