Ankylosing spondylitis is a disease that shows a young age of onset (less than 40 years old), inflammatory back pain, sacroiliitis and a strong association with HLA-B27. Yet some recently reported cases have presented with a late age of onset (more than 55 years old), atypical clinical presentations and a low response to NSAIDs, and this has also been named late onset spondyloarthropathy (LOSPA). As compared with early onset spondyloarthropathy (EOSPA), the LOSPA patients more frequently suffer with combined peripheral arthritis and inflammatory systemic symptoms and a high ESR and CRP level, but they lack the typical axial symptoms. Yet there have been few reports about late onset ankylosing spondylitis (LOAS). The previous cases of LOSPA and LOAS were managed with NSAIDs, steroids, methotrexate and sulfasalazine, but none were managed with TNF antagonists. LOAS is rare and difficult for management because of the patients' older age and the lack of experiences with this malady, so we report here on the four cases of LOAS that were successfully treated by TNF antagonists.

Keywords: Late onset, Ankylosing spondylitis, TNF antagonist