Background: Few studies have examined the association between autoimmune diseases and parkinsonism. Objective: We sought to investigate the risk for parkinsonism during a 5-year follow-up period after a diagnosis of psoriasis using a population-based data set in Taiwan. Methods: We identified 4885 patients with psoriasis for the study cohort and randomly selected 24,425 patients as a control cohort. Each subject was individually followed up for a 5-year period to identify those who subsequently developed parkinsonism. Results: Stratified Cox proportional hazards regression showed that the adjusted hazard ratio for parkinsonism during the 5-year follow-up period for patients with psoriasis was 1.74 (95% confidence interval 1.35-2.20) that of control patients. Furthermore, the adjusted hazard ratios for parkinsonism within the 5-year follow-up period after the index date for subjects with psoriasis were similar between both sexes (1.78 and 1.66 for men and women, respectively). Limitation: Our data set did not provide detailed information on the severity of psoriasis, or individual factors such as cigarette smoking, alcohol consumption, body mass index, and dietary patterns. Conclusion: Patients with psoriasis were found to be at a significant risk of parkinsonism during a 5-year follow-up.
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