Comparing diagnosis-related group systems to identify design improvements.

The objective of this research was to compare the casemix systems used in the United Kingdom (UK), Australia and the United States of America (USA) to identify possible improvements in the design of the UK Healthcare Resource Groups. The data consisted of over 12 million inpatient and day case discharge records from 574 National Health Service acute hospitals in England for 2001-2002. These data were grouped into four casemix systems, namely Versions 3.1 and 3.5 of Healthcare Resource Groups, the United States-based All Patient Diagnosis Related Groups, and the Australian Refined Diagnosis Related Groups. The statistical performance of the groups was measured using the reduction in variance (RIV) statistic. The Australian Refined Diagnosis Related Groups produced the best RIV overall but this grouper had the advantage of more groups than the others. The comparison of the performance of the chapters within each grouper showed that each had some chapters with a better RIV than the other groupers. Comparing the performance of these groupers was successful in identifying changes to the Healthcare Resource Groups that improved its performance. Further revision of the Healthcare Resource Groups should be focused on the chapters with the best potential for improved performance.