@Christian_Reich “Present on Admission” and “Admitting Diagnosis” are quite different. See my explanation in this July 2018 post: Present on Admission vs Admitting Diagnosis - #7 by aostropolets
You could have a POA condition (diagnosis) that is unrelated to the reason you were admitted. For example, you could have a pre-existing active decubitus ulcer, which would be a POI but be admitted for community-acquired pneumonia (admitting diagnosis).