In this chapter, we will discuss the APRDRG, or all patient refined diagnosis related group. It is another type of coding system that, unlike the Charlson Index, is proprietary and developed by the 3M Healthcare Company in 1990.(Anonymous-3M 2008) The APRDRG severity grouper is currently used by CMS (The Centers for Medicare and Medicaid) for severity adjusting all of Medicare’s hospital discharges. The 3M Company is also responsible for maintaining, updating and creating new DRG’s for CMS.Therefore, we cannot know what specific diagnosis codes are used to define the APRDRG severity index. In the APRDRG, patients are divided into one of four classes for severity of illness, and again divided into one of four classes for the risk of mortality.
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Diagnosis related groups (DRG) are used throughout healthcare. Providers are paid a set fee for a patient treatment. However, they are limited in that they do not distinguish between patient conditions; sicker patients require more resources and health costs, but reimbursements are the same as they are for healthier patients. The DRGs were originally implemented by Medicare for billing purposes. However, relying only on the DRG without any reference to patient condition results in underpayments to those providers who treat patients with the most severe conditions.(Antioch, Ellis et al. 2007) Problems with DRG in relationship to patient condition were identified early on.(McNeil, Kominski et al. 1988) DRGs are not accurate predictors of either costs or outcomes.(Gross, et al. 1988) One of the reasons is that complications resulting from care need to be distinguished from pre-existing conditions, and DRG codes (and ICD9 codes) do a poor job of this.(Young, Macioce et al. 1990; Naessens and Huschka 2004)
One attempt to identify patient risk and identify those who need more resources was the development of the refined DRG codes (RDRG). The RDRG codes subdivide the DRGs into levels of complexity that describe the patient condition. There are four general classes for RDRG refinement: no comorbid conditions, moderate comorbid conditions, major comorbid conditions, and catastrophic comorbid conditions, although only surgical patients qualify for the catastrophic class.(Leary, Leary et al. 1993) Therefore, there are four severity classes for surgical patients, but only three for medical patients. Clearly then, a higher proportion of surgical to medical patients will result in a higher proportion of patients in the highest category. A number of analyses have been performed to validate the RDRG, although problems have occurred with it as well.(Cerrito 2007) Another system developed by Medicare (MS-DRG) uses three tiers of severity to assign payments for specific DRGs.(Maurici and Rosati 2007) There are also a number of attempts to define severity adjustment for specific groups of patients.(Barbash, Safran et al. 1987)