Yes, as chiis says, you have to attend, but if your in a union, take a rep with you, I had to attend one of these, and all options will be discussed.
With my firm, and its something you'll have to find out, you get retired first, and then recommended for the medical, and if thats the way it happens, if they deem you employable, thats at anything at all, you don't get it, and if you do get it, they call you for a medical every year, and at any of these interviews, your deemed employable, they stop it.
As said, thats my firm, but I reckon the procedures will be similar.