If you ever wanted to filter requirements or other entities in HP ALM Quality Center by follow ups set for a user the below can give you a hint on how to do it.
Unfortunately I have not yet found a way to filter entities with follow up flags / alerts using a standard function in HP ALMs web interface.
The below SQL has been developed and used by one of my collegues who asked me how he could filter for all his requirements, which do have a follow up / alert set.
I told him I do not know any standard function but that there must be a way using the HP ALM Dashboard and SQL. We searched for the correct tables in the documentation and found the 'ALERT' table.
However this can be nice for power users, it is not yet a solution which I would hand to less skilled users since the user name has to be hard coded.
I will look into this and maybe provide a little script, which can do the trick using the HP ALM REST or OTA API but it is a shame that HP does not seem to provide a standard function for this simple task.