System alert - late Appointment Prompt

Think it would be really useful if there was a subtle alert when patients weren't ''arrived' at the point in time of their appointment, say + 3-4 minutes. This would initiate a call to chase or find out if patient is intending to keep the appointment. The overall objective would be to help manage tight clinician schedules, particularly when there are many patients coming in and out of clinic at the same time. As you may imagine, if patients are later than 5 minutes for their appointment, it can compromise their appointment as consequently, they may not get a full treatment. It also has a knock on effect and can potentially impact on other patients that follow during the rest of that day.