Drug survival of tumor necrosis factor α inhibitors in patients with ankylosing spondylitis in Korea

BACKGROUND/AIMS To evaluate drug survival of the tumor necrosis factor α inhibitors (TNFi) and risk factors for the drug discontinuation in patients with ankylosing spondylitis (AS). METHODS We retrospectively evaluated 487 AS patients at a single tertiary hospital. Among the TNFi users, drug survival and risk factors of TNFi discontinuation were investigated. RESULTS Among 487 patients, 128 AS patients were treated with at least one TNFi. Patients who were treated with TNFi were younger at disease onset, had more peripheral manifestations, and had higher level of acute phase reactants and body mass index than those of TNFi non-users at baseline. Of 128 patients, 28 patients (21.9%) discontinued first TNFi therapy during the follow-up period of 65.1 ± 27.9 months. In the multivariable analysis, female (hazard ratio [HR], 6.08; 95% confidence interval [CI], 2.27 to 16.27; p = 0.003), hip involvement (HR, 2.52; 95% CI, 1.08 to 5.87; p = 0.033) and a high C-reactive protein (CRP; HR, 1.10; 95% CI, 1.00 to 1.21; p = 0.044) were risk factors for drug discontinuation. Etanercept showed better survival rate than infliximab. The main reason for discontinuation of TNFi was inefficacy. CONCLUSIONS TNFi discontinuation rate of Korean patients with AS seems to be similar to those with the European patients. Female sex, hip involvement, CRP, and the type of TNFi were associated with TNFi discontinuation.