I need help writing a complex formula involving multiple dates corresponding to 1 data point

If just list of patients who had or didn't have something in 1Q2017 you may simply filter your table/data range by dates.

If such list is to be copied into another place, when Power Query or Advanced filter could work, as well as formulas.

However, to be more concrete with suggestions better to have small sample file which illustrates how your data is structured and which result is desired (all fields with patient data or only names, etc, and where to place).