Hi,
well, it might seem a bit silly to say, but for this you don't really need to have UCCX at all.
Let me just ask to make sure we are on the same frequency: you need an application that watches a database where the patients' phone numbers and the date and time of their appointments is stored, and if that appointment is approaching (let's say, it's in two days), then it places a call, and plays a static message, for instance "your appointment is in two days".
If so, you might need a different application, not UCCX. It cannot do the scheduling part, although it contains an automated dialer, but it's more like bulk dialling, for doing campaigns etc, you fill it up with a list of contacts and it just starts dialling them.
G.