After many discussions about the value of a collaborative association, including meetings in Paris in 1984 and Dublin in 1986, Patient Classifications Systems Europe (PCSE) was initially founded in 1987 in Lisbon. The organization created a network of researchers and users of the case mix concept from health administration, government agencies, and academia. From an initial focus on Diagnosis Related Group (DRGs), the association’s goals have expanded to include a broader interest in clustering and grouping techniques of clinical and administrative data for health care management and financing. The association has stimulated the use and refinement of the science of "grouping patients" within different levels of the health system.
Expansion of the organization throughout the world brought a name change from PCSE to Patient Classification Systems International (PCSI). It is the only worldwide organization addressing case-mix issues. In the last years the annual international conference has brought together a growing number of active participants from all over the world. From a group of six “idealists” from Western Europe and the United States, the organization has now grown to hundreds of members from 5 continents. The organization puts on one annual conference and offers educational opportunities through our summer and winter School programs.