Increased Risk of Pemphigus among Patients with Psoriasis: A Large-scale Cohort Study.

Although pemphigus has recently been linked to psoriasis, the risk of emergence of pemphigus during the course of psoriasis is yet to be delineated. The aim of this study was to evaluate the risk of developing pemphigus during the course of psoriasis. A large-scale population-based longitudinal retrospective cohort study was performed to assess the hazard ratio (HR) of pemphigus among 68,836 patients with psoriasis relative to 68,836 age-, sex-, and ethnicity-matched controls. The incidence of pemphigus was 0.14 (95% confidence interval (95% CI) 0.10-0.19) and 0.04 (95% CI 0.02-0.07) per 1,000 person-years among psoriatic patients and controls, respectively. Patients with psoriasis were more than 3 times as likely to develop pemphigus (HR 3.25; 95% CI 1.70-6.21). The increased risk remained statistically significant following adjustment for several confounders (adjusted HR 3.19; 95% CI 1.67-6.11). To conclude, psoriasis is associated with an elevated risk of pemphigus. Further research is needed to explore the immunoserological profile of patients with a dual diagnosis.