Objective: To determine the role of medication toxicity in the discontinuation of antirheumatic treatment among patients with ankylosing spondylitis (AS), and to compare the toxicity of different medications.
Methods: In a prospective longitudinal study of 241 patients with AS, we examined the duration of treatment and discontinuations due to side effects of new courses of sulfasalazine, methotrexate, ibuprofen, naproxen, indomethacin, diclofenac, piroxicam, nabumetone, and celecoxib.
Results: Of the 241 patients, 167 reported having a new treatment course of either sulfasalazine (n = 49), methotrexate (n = 19), ibuprofen (n = 105), naproxen (n = 57), indomethacin (n = 50), diclofenac (n = 38), piroxicam (n = 34), nabumetone (n = 27), or celecoxib (n = 25), for a total of 404 new treatment courses. Side effects were reported in 6.7% (ibuprofen) to 47.3% (methotrexate) of the courses. Between 2% (ibuprofen) and 23.5% (piroxicam) of courses were discontinued due to toxicity. For each medication, the duration of treatment was most often limited by factors other than toxicity. The time to drug discontinuation for any reason and the time to discontinuation due to toxicity did not differ between sulfasalazine and methotrexate. The time to drug discontinuation for any reason did not differ among nonsteroidal antiinflammatory drugs (NSAIDs), but discontinuations due to toxicity occurred earlier with piroxicam than with other NSAIDs.
Conclusion: Although medication toxicity is common among patients with AS, it is an uncommon cause of discontinuation of antirheumatic treatment.