The incidence rates and risk factors of Parkinson disease in patients with psoriasis: A nationwide population-based cohort study.

Abstract

The association between psoriasis and Parkinson disease has not been established. To determine the incidence rates and risk factors of Parkinson disease in patients with psoriasis. We conducted a nationwide population-based cohort study. The data from patients with psoriasis (N = 548,327, ≥20 years of age, 53.32% men and 46.68% women) and age- and sex-matched control patients (N = 2,741,635) without psoriasis were analyzed in this study. The incidence rates of Parkinson disease per 1000 person-years were 0.673 and 0.768 in the control and psoriasis groups, respectively. The psoriasis group showed a significantly increased risk of developing Parkinson disease (hazard ratio [HR] 1.091, 95% confidence interval [CI] 1.029-1.115). The risk of Parkinson disease was significantly higher among the psoriasis patients who were not receiving systemic therapy (HR 1.093, 95% CI 1.031-1.159) and lower among the psoriasis patients on systemic therapy (HR 1.04, 95% CI 0.806-1.316). The limitations of this study included the retrospective design, patient inclusion solely on the basis of diagnostic codes, and unavailability of data on confounding factors. Systemic anti-inflammatory agents might mitigate the risk of Parkinson disease in psoriasis patients.