Allergic Disease and the Risk of Rosacea and Psoriasis: A Population-Based Cohort Study Using a Large U.S. Database

Summary: Objectives: Rosacea, psoriasis, and allergic diseases are driven by inappropriate activation of the inflammatory cascade and are linked to similar pathomechanisms related to Th1 and Th17 pathways. Psoriasis has a higher incidence in individuals with allergic diseases including atopic dermatitis (AD), allergic rhinitis (AR), and asthma. Therefore, the incidence of rosacea may also be influenced by the presence of one or more allergic diseases similar to that seen in psoriasis. Methods: We investigated the association between allergic diseases (AD, AR, and asthma) and the risk of rosacea and psoriasis using data from the U.S. Collaborative Network on TriNetX. Individuals with allergic diseases AD, AR, and asthma were compared to a control group without allergic disease. The risk ratio with 95% confidence interval and number needed to harm (NNTH) were calculated. Results: Individuals with allergic diseases were at increased risk for rosacea and psoriasis, with similar risk ratios. Of the three allergic diseases analyzed, AD had the greatest association with rosacea and psoriasis, including when analyzed compared to a control group with other diseases of the skin. Conclusion: Allergic diseases are linked to an increased risk of rosacea and psoriasis which further supports a relationship between these diseases. However the number needed to harm did not indicate clinical significance.