Modified DRGs as evidence for variability in patient severity.

The authors were interested in exploring the extent to which differences in the complexity of patients could be determined by modifications in combinations of the ICD-9-CM codes used to define DRGs. The 150 most common medical and surgical DRGs in one teaching hospital were studied. With clinical experts they identified 41 DRGs that were believed to have subgroups reflecting quite different types of patients, one group sicker and costlier than the other. Using a national data set, the authors then showed that 24 of these DRGs showed significant differences in standardized charges. In 11 of these 24 DRGs the higher cost subgroups were seen proportionately more often in major teaching hospitals compared with other types of hospitals. Results suggest that clinical modifications of a few DRGs would lead to clinically more meaningful case-mix groupings. These same results can also serve as the basis for a discussion on the implication of DRG payments for those DRGs with distributional differences among the higher-cost subgroups.