Clustering of autoimmune diseases in patients with rosacea

Background: Rosacea is a common inflammatory skin condition that shares genetic risk loci with autoimmune diseases such as type 1 diabetes mellitus (T1DM) and celiac disease. A recent genomewide association study identified 90 genetic regions associated with T1DM, celiac disease, multiple sclerosis, and/or rheumatoid arthritis, respectively. However, a possible association with rosacea was not investigated. Objective: We evaluated the association between rosacea and T1DM, celiac disease, multiple sclerosis, and rheumatoid arthritis, respectively. Methods: We performed a population-based case-control study. A total of 6759 patients with rosacea were identified and matched with 33,795 control subjects on age, sex, and calendar time. We used conditional logistic regression to calculate crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Results: After adjustment for smoking and socioeconomic status, patients with rosacea had significantly increased ORs for T1DM (OR 2.59, 95% CI 1.41-4.73), celiac disease (OR 2.03, 95% CI 1.35-3.07), multiple sclerosis (OR 1.65, 95% CI 1.20-2.28), and rheumatoid arthritis (OR 2.14, 95% CI 1.82-2.52). The association was mainly observed in women. Limitations: We were unable to distinguish between the different subtypes and severities of rosacea. Conclusions: Rosacea is associated with T1DM, celiac disease, multiple sclerosis, and rheumatoid arthritis, respectively, in women, whereas the association in men only reached statistical significance for rheumatoid arthritis.