Paradoxical psoriasis in axial spondyloarthritis and rheumatoid arthritis treated with b/tsDMARDs: a retrospective...

To determine the incidence of paradoxical psoriasis (PP) across multiple b/tsDMARD classes, identify independent risk factors, and characterise the clinical features and treatment outcomes of PP in axial spondyloarthritis (axSpA) and rheumatoid arthritis (RA).

Single-centre retrospective cohort study of 1588 adult patients with axSpA or RA receiving at least one b/tsDMARD between January 2019 and December 2024. PP was defined as de novo psoriasiform skin lesions confirmed by dermatological evaluation. Incidence rates were calculated per 100 person-years. Risk factors were assessed by multivariable Firth penalised logistic regression and Kaplan-Meier analysis.

PP developed in 32 patients (2.0%) over 2795.7 person-years (incidence rate 1.14/100 PY; 95% CI 0.78-1.62). Thirty cases (93.8%) occurred with TNF inhibitors. No PP was observed with JAK inhibitors, rituximab, or tocilizumab. The predominant phenotype was palmoplantar pustular psoriasis (65.6%); median time to onset was 12.0 months (IQR 5.2-25.2). Ever-smoking was the sole independent predictor of PP (adjusted OR 2.15; p = 0.043); TNF inhibitor use and family history showed borderline associations. Kaplan-Meier analysis confirmed higher cumulative PP incidence in ever-smokers (log-rank p = 0.031). The causative b/tsDMARD was discontinued in 27 patients (84.4%); complete remission was achieved in 15 (55.6%).

PP occurs predominantly with TNF inhibitor therapy and is independently predicted by ever-smoking status. Palmoplantar pustular psoriasis is the predominant phenotype. Drug discontinuation leads to complete remission in the majority of patients, and non-TNF b/tsDMARDs may be considered as alternatives following PP development. Key Points • Paradoxical psoriasis occurs in 2% of axSpA and RA patients on b/tsDMARDs, almost exclusively with TNF inhibitors. • Ever-smoking is the sole independent predictor; smokers initiating TNF inhibitors warrant proactive skin monitoring. • Drug discontinuation achieves complete remission in most patients; non-TNF b/tsDMARDs are effective alternatives.