Clinical judgment and sometimes ethical judgment enter into these decisions where there are often no right or wrong answers and where there are no textbooks or RCTs that tell us what to do.
predecessor - something that precedes and indicates the approach of something or someone. harbinger, herald, forerunner, precursor. indicant, indication - something that serves to indicate or suggest; an indication of foul play; indications of strain; symptoms are the prime indicants of disease.
Successor(noun) one who succeeds or follows; one who takes the place which another has left, and sustains the like part or character; -- correlative to predecessor; as, the successor of a deceased king. Origin: [OE. successour, OF. successur, successor, F. successeur, L. successor.