The Risk of Mortality among Psoriatic Patients with Varying Severity: A Nationwide Population-Based Cohort Study in Taiwan

Background: Previous studies showed conflicting results regarding the mortality risk in psoriasis patients with respect to disease severity and presence of psoriatic arthritis. This study aimed to determine the mortality risk in patients with mild and severe psoriasis and patients with psoriatic arthritis (PsA). Methods: A nationwide population-based cohort study was conducted based on data from the Taiwan National Health Insurance Research Database between 2002 and 2012. Incident psoriasis subjects were classified into two groups: psoriasis without arthritis and psoriasis with arthritis. Patients who had received systemic therapy and/or phototherapy were classified as having severe psoriasis; otherwise, patients were classified as having mild psoriasis. Control subjects without psoriasis were selected to match each psoriasis patient from the database within the same observational period. Cox proportional hazards analysis was used to compare the hazard ratio (HR) of time to death. Results: A total of 106,701 patients with psoriasis were included in this study. After controlling for demographics and comorbidities, psoriasis patients had a higher mortality risk compared with the control group (HR 1.41; 95% confidence interval (CI) 1.36 to 1.46). Compared with psoriasis alone, the mortality risk was not increased for PsA (HR = 1.01; 95% CI 0.93 to 1.10). Besides, severe psoriasis did not increase mortality risk compared with mild psoriasis (HR = 1.0; 95% CI 0.95 to 1.06). Conclusions: Patients with psoriasis had a higher mortality risk compared with control subjects, whereas psoriasis severity and presence of PsA had no impact on mortality risk in psoriasis patients.