Comorbid diseases associated with pemphigus: a case-control study

Background and objectives: Pemphigus has been associated with physical and psychiatric comorbid diseases. This study aims to further investigate these associations in patients with pemphigus, and to analyze the relationships of comorbid conditions with sex and age, pemphigus disease area index score, diagnostic delay and cutaneous/mucous involvement. Patients and methods: Patients with pemphigus were matched by age, gender and area of residence with eight controls each. The odds of comorbid conditions in patients vs. matched controls was determined using univariate conditional logistic regression models. Comorbid diseases significantly associated with the diagnosis of pemphigus at P < 0.05 in univariate models were subsequently included in a multivariable conditional logistic regression model with a forward procedure. Results: The study sample included 163 patients with pemphigus. Cardiovascular diseases, hyperlipidemia, autoimmune thyroid disorders, dermatological autoimmune/inflammatory conditions and cancer were the most prominent conditions at the time of diagnosis. In the multiple conditional regression analysis, the two diagnoses independently associated with patients with pemphigus were cancer and dermatological autoimmune/inflammatory conditions. In sensitivity analyses excluding four patients with paraneoplastic pemphigus, these associations were still significant. Conclusions: Cancer and dermatological autoimmune/inflammatory conditions may represent possible triggering conditions for pemphigus and should be considered as early warning signs for the disease.