Predictors of Switching Anti-Tumor Necrosis Factor Therapy in Patients with Ankylosing Spondylitis

The aim of this study was to investigate the potential predictors of switching tumor necrosis factor (TNF)-α inhibitors in Korean patients with ankylosing spondylitis (AS). The patients who had been treated with TNF-α inhibitors were divided into two groups depending on whether they had switched TNF-α inhibitors. Demographic, clinical, laboratory, and treatment data at the time of initiation of TNF-α inhibitor treatment were compared between switchers and non-switchers, and within switchers according to the reasons for switching. Of the 269 patients, 70 (23%) had switched TNF-α inhibitors once; of these, 11 switched again. The median follow-up time was 52.7 months. Three- and five-year drug survival rates were 52%/48% for infliximab, 62%/42% for etanercept, and 71%/51% for adalimumab, respectively. Switchers were more likely to be prescribed disease-modifying anti-rheumatic drugs than non-switchers. A history of joint surgery and complete ankylosis of the sacroiliac joint was more frequent in switchers. Multivariate Cox's proportional hazard analysis showed that the use of adalimumab as the first TNF-α inhibitor was less likely to lead to switching and complete ankylosis of the sacroiliac joints was more likely to lead to switching. The principal reasons for switching were drug inefficacy and adverse events, but the differences in the clinical data of these two groups of switchers were not significant. In AS patients who are candidates for TNF-α inhibitor therapy, switching may improve the therapeutic outcome based on clinical information.