This seems like something that AC's built-in reporting system should easily do, but that does not appear to be the case.
As Bert points out, I would imagine that you have little interest in identifying patients who missed in the distant past. Further, you want them to disappear off the list as time goes by.
Gerardo, it looks like you invest some significant effort in trying to contact these patients as well as keeping track of those attempts, so you might consider the following:
Create a series of flags.
1= missed appointment
2= missed appointment, called patient
3= missed appointment, letter written
At the end of the day, have someone set a flag "1" on each patient who does not show.
At the end of the month (or whenever) run a report "flag=1" to create your list.
As the patients are called and not reached (so you need to take the next step in follow-up), as the staff goes down the list they change the flag to "2".
A but cumbersome, but I would expect this is less effort than maintaining a separate spreadsheet.
