Modes of DRG refinement

There are several DRG systems with the name extension "refined". This usually stems from the introduction of additional graduation of severity as part of further developing an earlier system. However, there are many ways such refinements had been carried out in time.1

The first DRG system which was called "refined" was the RDRG system presented in 1989. The background for this was to refine the distinction between DRGs "with CC" (DRG with co-morbidity or complications) and DRGs "without CC" used in the HCFA-DRG system. Thus, the RDRG system split up medical cases into three and surgical cases into four CC levels.

Later, American developers applied the term to other forms of refinement, as well, so that the word "refined" today can mean different things. [Tables 1 und 2] It is though common to all these aspects that they always try to provide an ever more differentiated representation of severity of a case:

• All refined systems use more than two CC levels.
• Usually, there are several CC lists used for refinement (except in IR-DRG, SR-DRG and MS-DRG). This allows to define the severity of the secondary diagnoses in function of the base DRG and – if needed – of other criteria. (The ARDRG system uses a compilation of these lists in the shape of the "CCL matrix".)
• In some of the systems (APR-DRG and AR-DRG), combinations of several secondary diagnoses have an influence on the CC level. In other systems, the secondary diagnosis which triggers the highest CC level is chosen.

In parallel to the above, most systems also use age groups, more or less frequently, to re­present differences in the severity of cases.

Table 2 provides an approximate overview of the evolution of systems in relation to increasing differentiation of refinement,

Other approaches to represent the severity of acute inpatient cases were applied by: Disease Staging, PMC, EfP-GHM, LDF, as well as in the SQLape system developed by Yves Eggli (Lausanne). Another completion to conventionally structured DRG systems is represented by "unbundled HRGs" and by "supplementary fees" ("Zusatz­entgelte") in the GDRG system.