DRGs: the state of the art, circa 1990.
The history, up to 1990, of operational DRG systems in the United States is described from the viewpoint of changes to the patient classification system. Uses of DRGs, the DRG assignment process and the clinical verification steps are also described. The DRG classification process has become more precise over the last decade in both detail and structure. The annual revision process used in the U.S. is outlined with a detailed summary of historical changes. Recent improvements to DRGs have been directed towards a higher degree of precision as regards patient severity and related resource intensity. Recent research into modifying DRGs to better account for complexity or severity is presented with some scenarios for future developments.