Increased Risk of Dermatomyositis in Patients with Psoriasis: A Retrospective Cohort Study.

Purpose: This study aimed to investigate the risk of dermatomyositis among patients with psoriasis in a large population.

Patients And Methods: Individuals aged ≥20 years with records in the TriNetX database from January 1, 2002 to December 31, 2022 were included. Diagnoses of psoriasis, non-psoriasis, dermatomyositis, and associated comorbidities were established using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) code. Patients who were diagnosed with dermatomyositis before the index date were excluded. Propensity score matching (PSM) was performed in a 1:1 ratio between the psoriasis group and non-psoriasis group. Kaplan-Meier curves were used to determine the cumulative incidence of dermatomyositis, and the Cox proportional hazard model was used to estimate the hazard ratio between the two groups.

Results: After PSM, 301018 individuals were included in the psoriasis and non-psoriasis groups, respectively. A higher risk of dermatomyositis was identified in patients with psoriasis than in those without (HR: 2.41, 95% CI: 2.01-2.89). This elevated risk was further confirmed in various subgroup analyses. Specifically, patients with PsA exhibited a higher incidence of dermatomyositis than those without PsA (HR, 1.73; 95% CI, 1.32-2.28). Patients treated with interleukin-17 inhibitors (IL-17i) showed a significantly higher risk of developing dermatomyositis compared to those naïve to biological agents (HR, 5.79; 95% CI, 1.57-21.31). In the European, Middle East, and Africa network and Asia-Pacific network, the risk of dermatomyositis in patients with psoriasis was higher than that in patients without psoriasis (HR (95% CI): 4.77 (1.40-16.10) and 2.50 (1.33-4.66), respectively).

Conclusion: This study revealed a higher risk of dermatomyositis in patients with psoriasis than in those without. The psoriatic patients with PsA or those who had received IL-17i treatment demonstrated a significantly higher risk of developing dermatomyositis.