Incident psoriasis in atopic dermatitis: a large-scale cohort study of disease- and treatment-associated risks.

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 that type 2-targeted biologics may unmask psoriasis in patients with AD, 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 Open Science Framework, and confirmatory execution. Propensity score-matched analyses compared AD with non-AD controls and biologics with cvIS. Sensitivity analyses, including multivariable Cox proportional hazards (CPH) analyses, and control outcomes assessed robustness.

RESULTS

Among ~300,000 matched pairs, AD was associated with increased psoriasis risk [primary hazard ratio (HR) 3.81, 95% confidence interval (CI) 3.35-4.34], consistent across all eight sensitivity analyses and CPH. Biologic treatment was associated with reduced psoriasis risk versus cvIS (primary HR 0.20; 95% CI 0.11-0.35), consistent across eight of nine evaluable sensitivity analyses and CPH. Positive and negative control outcomes showed expected directional patterns.

CONCLUSIONS

Acknowledging limitations including residual confounding and coding misclassification, AD was associated with increased psoriasis risk and biologics with lower psoriasis risk than cvIS.