Short Info: PMC (USA)

The PMC system1 is an American competition model to the DRG systems, developed during the 80s. This system assigns not just one, but several disease categories to any individual hospital stay, if necessary. All diagnoses are considered without any ranking (unlike in most DRG systems where only the first, so-called "principal diagnosis", is relevant).

However, since not each diagnosis describes a unique clinical condition, 54 disease/disorder modules have been defined (e. g. appendicitis, vascular disorder, delivery, lung neoplasm etc.). From each selected module, the PMC best reflecting the severity of the respective disease is assigned to the hospital stay.

This approach allows for the following severity concepts to be considered:

• Multi-morbidity (several organs/body systems affected) is represented by assignment of PMCs from different modules.
• The representation of severity within an individual disease (disease stage) is done by assigning defined diagnosis combinations belonging to the same disease to different PMCs within the same corresponding module.2
• In addition to the above, an aggregated severity level of all clinical conditions for each hospital stay is represented by means of a seven-step severity level indicator.
• Additional patient conditions defined by nurses could be integrated into the PMC model as an extension to the existing system: additional nursing related modules could be created.

Assignment of several patient categories to a single hospital stay implies some difficulties as well: Since a patient presenting two diseases is admitted only once, reference costs (or cost weights, respectively) from the individual patient categories cannot be simply added to obtain a total cost weight for the said hospital stay.

The PMC's solution to this problem is as follows: For each PMC, a typical patient management path was elaborated. For each step in treatment contained in this pathway, individual cost weights are calculated. When more than one PMC is eligible for the same hospital stay, the total cost weight is computed aligning all corresponding patient management paths and taking from these the highest given cost weight for each treatment step.