Comparing Patient Spectra
by Difference Diagrams

How can one visualise the particularities of the casemix of a hospital?

The necessary data from the hospital concerned and all the hospitals of a reference group are case records containing DRG codes. The DRG codes are classified by MDCs, subcategories ("M" = medical, "C" = surgical) and cost weight classes ("1" to "4").

The differences of portions of cases between the hospital concerned and the hospitals in the reference group are shown by the triangles of «difference diagrams»1 (developed by the author), arranged by means of graphic panels ("trellis displays")2, one for each MDC.

This kind of graphic enables us to see negative and positive deviations (dull colour/clear colour) of medical and surgical cost weight classes (green/golden) within MDCs of the full casemix of a hospital at a glance.

In order to obtain a simpler graphic, cost weight classes can be omitted. Then only two triangles will remain in each panel.

This is a new type of graphics helping to provide a "detailed overview" of DRG data.