Comparison of the Risk of Paradoxical Psoriasis between Monoclonal Antibody and Non-monoclonal Antibody Tumor Necrosis Factor-<i>α</i> Inhibitors in Patients with Rheumatoid Arthritis: An Observational Study Using a Claims Database

Tumor necrosis factor-α inhibitors (TNFis) are associated with a risk of paradoxical psoriasis, but quantitative data remain limited. One proposed mechanism is the induction of interferon (IFN) production following TNFi administration. Etanercept and certolizumab pegol, which contain immunoglobulin fragments in their structures, reportedly induce IFN production in T cells more than monoclonal antibody (mAb) TNFi agents. Based on this, we hypothesized that non-mAb TNFi agents might carry a higher risk of paradoxical psoriasis than mAb agents. This study compared the risk of paradoxical psoriasis between mAb and non-mAb TNFi agents in rheumatoid arthritis (RA) patients. Using a claims database, we identified 1577 subjects in the mAb group and 1517 in the non-mAb group. Patient characteristics, including sex, age, and prior RA treatment, were extracted, and the onset of psoriasis was identified. Multivariable Cox regression analysis showed the hazard ratio (HR) for psoriasis onset in the mAb group versus the non-mAb group was 1.66 (95% confidence interval [CI]: 0.79-3.48). Subgroup analyses revealed that compared to etanercept, the HR for adalimumab was 1.43 (95% CI: 0.49-4.19), and compared to certolizumab pegol, it was 0.67 (95% CI: 0.19-2.39). These findings suggest that our hypothesis was not supported and that the risk of paradoxical psoriasis may vary even among non-mAb agents, as indicated by differences observed between etanercept and certolizumab pegol.