Health Information Management

Q&A: Defining differences in DRG systems

CDI Strategies, December 24, 2009

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Q: What are the differences between the MS-DRG and the APR-DRG systems? 

A:Garri L. Garrison: Medicare Severity-Diagnosis Related Groups (MS-DRG) is a severity-based system. Within it there are three choices of MS-DRG assignment for a particular diagnosis. For example, with a diagnosis such as heart failure, the choices include with a complication comorbidity (CC), with a major CC, and without either a CC or MCC. Under the MS-DRG system it only takes one secondary diagnosis to move the patient’s care into one of those three assignments. The other conditions coded on case will have no impact. So the patient might have five CCs, but will only be assigned to the DRG based on one CC. 

In contrast to MS-DRGs, full severity-adjusted systems do not just look at one diagnosis. These systems take into account other conditions, and by having additional conditions, the patient may move into a higher complexity case based on the interaction of all conditions together. MS-DRGs only give you credit for partial severity but if you go to a full severity-based system, then all the conditions are incorporated into the decision of the DRG assignment.
Shelia Bullock: MS-DRGs are used more for our older population, and severity adjusted DRGs (like APR-DRGs) take into effect all age ranges, especially the pediatric population. 
Garri L. Garrison: Most of the severity adjusted systems handle any type of population, whether it’s commercial or Medicare or Medicaid, and they do take age into account. So there are adjustments to the system based on the conditions that occur in those different age groups. Whereas when MS-DRGs came out, CMS was very clear this system really was not designed for use outside the Medicare population.
Editor’s Note: The above question and answer is from the September 18, 2009 audio conference “Severity of Illness and Risk of Mortality: Sharpen Your CDI Focus with New Measures of Success,” by Garri L. Garrison, RN, CPC, CMC, CPUR, director of acute care services for 3M Health Information Systems Consulting Services in Atlanta, and Shelia Bullock, RN, BSN, MBA, CCM, CCDS, manager of clinical documentation services for the University of Mississippi (Jackson) Medical Center.

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