Disease staging--a case-mix system for purchasers?

The National Health Service (NHS) internal market has directed renewed attention at hospital activity data. Purchasers require information on the cost of care provided for them, the quality of service and the extent to which their population's needs are being met. There is a need for a means of condensing the large number of diagnostic codes into groups containing patients with similar outcome or resource use, i.e. case-mix systems. These systems have been developed in the United States to overcome this problem. Unfortunately, they may not be valid or acceptable in other countries. We describe the evaluation of one such system, Disease Staging, in the United Kingdom. We conclude that it can be used with UK data to produce groups that are homogeneous both in terms of length of stay and mortality. Its logic is acceptable to UK clinicians. We discuss the major issues involved in using routine hospital data and suggest ways in which Disease Staging might be used by purchasers in the UK internal market.