Ankylosing spondylitis: open long-term and double-blind crossover studies with naproxen

Participation in open and double-blind crossover studies in rheumatoid arthritis confirmed that naproxen improved pain and stiffness. This observation suggested that naproxen might be effective in ankylosing spondylitis. The initial trial was open, but at six months, a double-blind crossover "placebo pulse" was superimposed on the open trial. Thirty-six patients entered the trial taking a daily dose of 500 mg naproxen. At the end of the first month, 35 assessed naproxen as being equally effective to, or better than, previous therapy. The first ten patients to complete six months on naproxen took part in a placebo pulse study comprising two consecutive four-week periods, in one of which each patient took 500 mg naproxen, in the other, identical placebo capsules, the order being randomized. Eight patients correctly identified the placebo capsules (P=0.02). During the 16 months of trial, six patients have withdrawn, two being in remission and four for lack of efficacy. The remaining 30 patients have completed six months and 22 have completed at least 12 months on naproxen. At the end of six months pain was less (P=0.02), morning stiffness had decreased (P less than 0.01), and immobility stiffness had improved (P less than 0.01). These patients are impressed by the improvement in pain and stiffness and have little disability. All continue full-time employment and have been able to increase their leisure activities without discomfort. No persistent side effects were observed, and naproxen appears to be a useful drug in the treatment of anklyosing spondylitis.