  Background: Transitioning from an old medical coding system to a new one can
be challenging, especially when the two coding systems are significantly
different. The US experienced such a transition in 2015. Objective: This
research aims to introduce entropic measures to help users prepare for the
migration to a new medical coding system by identifying and focusing
preparation initiatives on clinical concepts with more likelihood of transition
challenges. Methods: Two entropic measures of coding complexity are introduced.
The first measure is a function of the variation in the alphabets of new codes.
The second measure is based on the possible number of valid representations of
an old code. Results: A demonstration of how to implement the proposed
techniques is carried out using the 2015 mappings between ICD-9-CM and
ICD-10-CM/PCS. The significance of the resulting entropic measures is discussed
in the context of clinical concepts that were likely to pose challenges
regarding documentation, coding errors, and longitudinal data comparisons.
Conclusion: The proposed entropic techniques are suitable to assess the
complexity between any two medical coding systems where mappings or crosswalks
exist. The more the entropy, the more likelihood of transition challenges.
Users can utilize the suggested techniques as a guide to prioritize training
efforts to improve documentation and increase the chances of accurate coding,
code validity, and longitudinal data comparisons.
