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Understanding the Importance of the OASIS

If you are an RN or therapist in the home health setting, you are familiar with the OASIS. You may not know why or how the OASIS is used. The Outcome and Assessment Information Set (OASIS) is integral to home health providers and is the source for the HHRG, which determines reimbursement for care.

Components of the OASIS

The OASIS also allows monitoring and reporting quality measures, including outcomes and process:

Did the patient improve functional ability to groom self or dress upper and lower body?

Did the agency see the patient in a timely manner?

These assessments are reported in Home Health Compare scores and can impact a provider’s ability to attract referrals. The provider can also use these measures to inform their QAPI program. Learning to accurately complete the OASIS can positively impact a provider in multiple ways.

Assessing the Impact

On a broader scale, the data collected for the OASIS is used to make decisions for the industry. For example, CMS found that they were incentivizing therapy use when the population did not need more therapy, thus the change reflected in the upcoming Patient-Driven Groupings Model (PDGM) that therapy utilization does not increase reimbursement alone. Medicare will accommodate for therapy for diagnoses that will require therapy for optimal recovery.

The OASIS data is standardized to compare care across home health, acute care in hospitals and skilled care in a rehab or nursing facility. The data obtained from the OASIS allows CMS to make decisions related to reimbursement, and which setting is most efficient and cost-effective for the disease treated. Industry-wide changes are made based on clinician assessments.

Comprehensive Assessment

The comprehensive assessment is not the same as the OASIS. The OASIS data are the questions that inform CMS. The comprehensive assessment is the actual environmental and emotional assessment performed by the clinician during a visit. The OASIS and the comprehensive assessment have been combined for convenience so that the clinician can assess and answer both needs at the same time.

Performing an OASIS

There are rules as to who can perform an OASIS assessment for the information to be used by Medicare. Currently, a registered nurse (RN), physical therapist (PT), occupational therapist (OT), and speech language pathologist (SLP) may complete an OASIS. If a nurse is involved in the care, a nurse must complete the Start of Care (SOC) OASIS. Physical therapy or speech therapy-only cases may have the OASIS completed by the respective disciplines. At Start of Care, however, an OT may not complete the OASIS as OT services alone do not warrant home health care. The OT may complete the subsequent OASIS if they are the only remaining discipline under Medicare. Under Medicaid, the OT can establish eligibility and may complete an OASIS at Start of Care.

The OASIS Guidance Manual from CMS outlines the timepoints for when an OASIS assessment must be completed as these are significant timepoints that will change the care provided. They also inform Medicare of the medical necessity of care and the potential costs of care. Tracking costs of care allows preparation of future Medicare benefits.

Start of Care (SOC): This information is collected at Start of Care.
Resumption of Care (ROC): This information is collected at Resumption of Care when a patient has been transferred to another provider and then returned.
Follow-Up (FU): This information is collected at Recertification and Other Follow-Up or for a significant change in condition.
Transfer (TRN): This information is collected at Transfer to Inpatient Facility, with or without Discharge from Home Health Agency.
Discharge (DC): This information is collected at Discharge from Home Health Agency other than Death at Home or Transfer to Inpatient Facility.
Death at Home (Death): This information is collected when the patient dies while on service with the home health agency, and died somewhere other than an inpatient/outpatient facility or ED.


The time to complete an OASIS is guided to provide timely care to the patient, but also to provide consistent and comparable information to Medicare.

  • The M0090 date is the date the gathering of information is complete. This is not necessarily the date that documentation is complete.
  • OASIS must be submitted to CMS within 30 days.
  • Start of Care assessment must be completed within five days of the Start of Care date.
  • Resumption of Care assessment must be completed within 48 hours of the patient’s return home (or knowledge of patient’s return from an inpatient stay) or within two calendar days of the physician-ordered ROC.
  • For Transfer to Inpatient Facility, Discharge from Homecare, Death at Home or Other Follow-Up, the assessments must be completed within 48 hours of becoming aware of the event.
  • With PDGM, the two 30-day payment periods will require completed documents in half of the time as there are two billing periods. Each billing period will require completed OASIS, as well as other documents.

CMS is focused on patient-centered care that provides quality and efficiency. The OASIS informs CMS whether this care is provided and gives data to see trends that inform care provided in the home. Clinicians help their agency and the healthcare industry by accurately completing the OASIS in a timely way.

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