[JshWright]

The most charitable option is that PF had some sort of tooling to allow folks other than engineers to create new CDS alerts, and that system already had all the info it needed to render these new alerts. If they had such a system, and if they were just using pain related diagnoses or something, it's possible no engineering effort was required (such a system would certainly already be able to consider the pt's diagnoses).

In my experience (working with similar systems at a different EHR), these things are complicated, and you pretty much never get away with zero engineering effort. That effort might have been limited to "Expose the patients last three reported pain levels to the CDS system", or it could have been much more involved.