Navigate to Setup > Create > Objects > Appointment > Result. Scroll to Field Dependencies section and edit the Result Detail:
Here, you'll find all of the Result options across the top, with the Result Detail options below each Result. Double click on the new Result Detail under each Result you'd like to it be under:
You can use the Preview button to see how the Field Dependencies will appear to your Users.
Save and you're all set!
NOTE: If you need to add Values to the Result Detail field, navigate to the Appointment object and select the Result Detail field in the Custom Fields and Relationships section. From there you can add or remove Result Detail values.
Also refer to this video on Editing Picklist Values: