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Written by: Darlene D'Altorio-Jones (1959-2015) on Wednesday, February 23, 2011 Posted in: Inpatient Rehab

There is a “behind the scenes” need to understand the value of CMI in a rehabilitation facility and why it’s important to capture appropriate functional scores, co-morbid conditions and the correct impairment group code.

The Case Mix Groups (CMG) are weighted and each is assigned a Case Mix Index (CMI) which reflects the burden of care or “cost index” associated with that CMG. The 1.0 level is the “standard” Medicare reimbursement rate, not yet affected by facility adjustment factors.   Burden is defined by the mix of resources required to care for the patient and are captured in the PAI tool. The PAI and cost reporting on like patients creates annual updates to payment CMI indexes and length of stay averages. These are published each year in the regulations for IRFs.

Therefore, infections, meds, wound care, etc., along with cost reports; create future CMG and CMI weight changes. Those changes are a direct result of cost report studies and PAI history. Indirectly (on average) the care or burden that specific patients demand in rehabilitation is reflected in the CMI. This is the basis of the neutral payment methodology: a cost to care for the patient is determined and that burden is assigned a weight that will “on average,” cover care costs. CMI is a reflection of practice and resource needs.

Unique functional needs and training of severely impaired rehab patients is often lost in medical/surgical acuity model reviews. However, the CMI of 2.2 stroke patient over a .67 joint replacement patient is widely understood by nursing and already Medicare accepted to reflect cost and burden of care.

Recently, a senate bill was introduced to the 112th Congress that is now in Finance Committee which could impact all states as it relates to acuity staffing by patient need. On January 25, 2011, there was a proposal for SB 58 called “Registered Nurse Safe Staffing Act of 2011,” which can be read at:

It is feasible that CMI can be used to demonstrate patient improvement.  As the patient becomes more self-capable, functional scores improve and acuity is reduced along with nursing care requirements reflected by a lower CMI from admission.

More than any other time, it would be beneficial for nursing to educate the in depth purpose of the PAI tool and to critically commit to functional assessment measurement as a key component to establishing resource allocation based on changing CMI and to substantiate rehabilitation nursing from standard acute care models.

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