Higher body mass index and anti‐drug antibodies predict the discontinuation of anti‐TNF agents in Korean patients with axial spondyloarthritis

Objective The development of anti‐drug antibodies (ADAbs) against tumor necrosis factor (TNF) inhibitors is a likely explanation for the failure of TNF‐inhibitors in patients with spondyloarthritis (SpA). Our study determined the existence and clinical implications of ADAbs in axial SpA patients. Methods According to the Assessment of SpondyloArthritis International Society classification criteria for axial SpA, patients treated with adalimumab or infliximab were recruited consecutively. Serum samples were collected at enrollment to measure ADAb and drug levels. Results Of 100 patients, the mean duration of current TNF inhibitor use was 22.3 ± 17.9 months. ADAbs were detected in 5 of 72 adalimumab users compared to 5 of 28 infliximab users (6.9% vs. 17.9%). ADAb‐positive patients had a significantly higher body mass index than ADAb‐negative patients among both adalimumab (28.4 ± 5.9 kg/m² vs. 24.3 ± 2.9 kg/m², respectively, p = 0.01) and infliximab users (25.9 ± 2.8 kg/m² vs. 22.6 ± 2.8 kg/m², respectively, p = 0.02). During the median 15‐month follow‐up period, drug discontinuation occurred more frequently in the ADAb‐positive group than the ADAb‐negative group (30.0% vs. 6.5%, respectively, p = 0.04). In logistic regression, ADAb positivity (OR = 5.85, 95% CI 1.19–28.61, p = 0.029) and BMI (OR = 4.35, 95% CI 1.01–18.69, p = 0.048) were associated with a greater risk of stopping TNF inhibitor treatment. Conclusions Our result suggests that the presence of ADAbs against adalimumab and infliximab as well as a higher BMI can predict subsequent drug discontinuation in axial SpA patients.