How and why does the order of the co-existing ICD-9-CM codes affect the predicted duration values?
The predictive model assumes that the first co-existing code is the most important, the second one entered is the one of next importance, and the third one is of least importance–weighting the effects of the codes appropriately. This weighting, combined with taking into account how various coexisting conditions interact with the primary condition, results in different predicted durations depending on the order in which the co-existing codes are entered into the model.
