That's 3 week reduction from 40mg to 0mg of prednisone, after 18mths of prednisone use - that's unheard of. Fast reductions to zero are only done with short term prednisone use (2 -3wks), though pulse increases and a return to what you were currently taking or somewhere near it are sometimes done. What does he propose happens after that? If you've understood his instructions correctly, I'd be finding a new doctor.