Radiographic progression in patients with ankylosing spondylitis according to tumor necrosis factor blocker exposure: Observation Study of Korean Spondyloarthropathy Registry (OSKAR) data

Objective: To evaluate the influence of tumor necrosis factor (TNF) blocker on the radiographic progression in ankylosing spondylitis (AS) patients. Methods: A total of 610 patients were recruited. We stratified two groups (TNF blocker naive and exposure patients). After then, we analyzed the radiographic spinal progression. Univariable and multivariable analyses were performed to identify predictors associated with radiographic progression, which was assessed by the modified Stokes AS Spinal Score (mSASSS). As this was an observational study, the patients were not randomized to the treatment arm. Therefore, propensity score matching was also done with age, gender, and the baseline CRP. The generalized estimating equation model was performed in the post-matched samples. Potential confounders were included in the model. Results: Agreements between the two readers were excellent. Of the 610 patients with AS, 341 patients did not have any exposure to TNF blocker. The radiographic progression (mean +/- SEM) was not significantly different between groups (4.73 +/- 1.01, and 6.14 +/- 2.00, P=0.54) in spite of adjusting for confounding factors (age, gender, disease duration, smoking, CRP level, NSAID intake, and baseline mSASSS). Propensity score matching was done to confirm the effect of TNF blockers on radiographic progression. Even after adjusting for the TNF blocker exposure, the result still remained not significant with an OR for progression while taking TNF blocker of 0.69 (P=0.41; 95% CI: 0.29-1.63). Conclusion: Our registry data showed that TNF blocker failed to affect the radiographic progression over 5 years in AS patients. (C) 2016 Published by Elsevier Masson SAS on behalf of Societe francaise de rhumatologie.This study was supported by grants from the National Research Foundation of Korea (NRF) Grant funded by the Ministry of Education, Science, and Technology (grant no. 2011-0008867) and by the Chonnam National University Hospital Research Institute of Clinical Medicine (grant no. CRI 11074-21)