Review of cohort data finds AD linked to psoriasis risk and biologics associated with lower risk.

Background. Clinical and genetic evidence on the association between atopic dermatitis (AD) and subsequent psoriasis remains conflicting, and it is unclear whether this risk is modified by systemic treatments. Recent reports suggest type 2-targeted biologics may unmask psoriasis in AD patients, but data are limited. We thus aimed to assess whether AD is associated with incident psoriasis and whether this risk differs by systemic treatment, particularly biologics versus conventional systemic immunosuppressants (cvIS). Methods. Scoping analyses informed a locked analytic design, preregistration at OSF, and confirmatory execution. Propensity score-matched analyses compared AD with non-AD controls and biologics with cvIS. Sensitivity analyses, Cox model triangulation, and control outcomes assessed robustness. Findings. Among ~300,000 matched pairs, AD was associated with increased psoriasis risk (primary HR 3.81, 95% CI 3.35-4.34), consistent across all 8 sensitivity analyses and model triangulation. Biologic treatment was associated with reduced psoriasis risk versus cvIS (primary HR 0.20, 95% CI 0.11-0.35), consistent across 6 of 7 evaluable sensitivity analyses and Cox triangulation. Positive and negative control outcomes showed expected directional patterns. Interpretation. Acknowledging limitations including residual confounding and coding misclassification, AD was associated with increased psoriasis risk and biologics with lower psoriasis risk than cvIS. Funding. DFG (EXC2167, SFB1526, LU877/25-1), Schleswig-Holstein Excellence-Chair Program, Swedish Society for Dermatology and Venereology, and the Tore Nilson Foundation.