Major depressive disorder increased risk of psoriasis: A propensity score matched cohort study.

Abstract Background Reports showed that elevated proinflammatory cytokines, as detected in patients with psoriasis, was noted in individuals with major depressive disorder (MDD). Therefore, this study aimed to clarify the association of MDD and prospective incidence of psoriasis in human using a nationwide study. Method This population-based cohort study used the data from the Taiwan National Health Insurance system. 64,486 patients were defined as MDD cohort and 64,486 propensity score matched subjects without MDD were identified as comparison cohort. Each patient was independently tracked for a 5-year study period to assure them for a psoriasis diagnosis after the index date. Stratified Cox proportional hazard models were used to calculate the hazard ratio (HRs) for 5-year psoriasis risk. Results After adjustments, the HR of psoriasis for MDD patients was 1.32 compared with subjects without MDD. The stratified analyses present that MDD patients had approximately 1.30-fold significantly higher risk of psoriasis than comparison subjects in most subgroups. Furthermore, compared with the matched subjects without MDD, the adjusted HRs of psoriasis in the 2-, 3-, 4- and 5-year study periods were 1.33, 1.32, 1.33 and 1.32, respectively. Limitations Several patients with MDD or psoriasis might not include in this study, because of using a medical claims database. Conclusions This study provides population-based evidence that MDD is an independent risk factor of developing psoriasis, with an increased risk in the male sex. Additional investigations verifying our findings and exploring possible pathological mechanisms would be of great interest and value to the psychiatric field.