Update on the treatment of ankylosing spondylitis

Non-steroidal anti-inflammatory agents (NSAIDs) remain the mainstay of treatment for ankylosing spondylitis (AS) though one recent trial suggests that continuous as opposed to on-demand use may be superior in preventing progression of structural damage. One particular NSAID, which is a highly selective cyclo-oxygenase 2 inhibitor, etoricoxib, may be superior to standard NSAIDs for AS. Second-line agents typically used for rheumatoid arthritis appear to lack efficacy. Salazopyrin is only moderately effective in the subgroup of AS patients with concomitant peripheral arthritis and not in those with purely axial disease. A recent trial showed that there is no greater efficacy in patients presenting early in their disease course. Three anti-tumor necrosis factor alpha agents, infliximab, etanercept, and adalimumab, are now available for the treatment of AS, the latest being adalimumab. All possess similar clinical efficacy in phase III trials with response rates of about 60%. Imaging studies using magnetic resonance show substantial amelioration of inflammatory lesions in the spine and sacroiliac joints. There is as yet no evidence that any of these agents prevent progression of structural damage. One study that evaluated etanercept demonstrated no impact on damage progression. Increasing evidence points to the superiority of the two monoclonal antibodies, infliximab and adalimumab, over etanercept for the treatment of extra-articular manifestations typically seen in AS such as acute anterior uveitis and inflammatory bowel disease. All three agents can be used as monotherapy and concomitant methotrexate appears to offer no advantages although insufficient doses have been used to date. Future studies should target patients earlier in their disease course as well as those with adverse prognostic factors such as elevated serum metalloproteinase 3 levels and radiographic evidence of spinal ankylosis.