There are different versions of AS, and thus different remissions. When I first got AS, my disease went in and out of remission for no apparent reason. I thought various diets did it, but no because it would come back. I would have it for 6 months and then 2/3 years of remission. I could never get diagnosed because by the time I saw doctor, I was in remission with nothing wrong with me except I could barely touch my knees let alone toes.
Then my disease got really severe in my 40's, and drug induced remission was for only a short time and then the medication would "turn to water". After I finally found the right drug, I have been in drug induced remission for over 5 years. It is shaky though. If I am late with the drug, it starts coming back and I can still over do it. Plus the damage has not gone away.
Actema IV once a month (with pre loading for allergic reaction), Cymbalta x1 daily, Arava 20mg daily. Diagnosed with AS in 2004, suffered undiagnosed since 1982.