I think this article will be of interest

Continuous NSAID use beneficial in ankylosing spondylitis

Jun 2, 2005
"We conclude that a strategy of continuous use of NSAIDs decreases the radiographic progression in patients with AS without substantially increasing toxicity. While awaiting confirmation of these results, we carefully recommend that if patients need treatment with NSAIDs to reduce the signs and symptoms of AS, they should take NSAIDs continuously instead of as needed based on symptoms."

http://www.rxpgnews.com/ankylosingspondy...1607_1607.shtml