Objectives: The risk of herpes zoster (HZ) between patients with psoriasis receiving and not receiving systemic therapy has received increasing attention. This study investigated the association of psoriasis with the risk of HZ. Methods: We conducted a population-based retrospective cohort study by using the Taiwan National Health Insurance Research Database. The psoriasis cohort consisted of 4077 patients with newly diagnosed psoriasis between 2000 and 2006. Each patient with psoriasis was frequency-matched with four people without psoriasis, by sex, age and index year. (nonpsoriasis cohort; 16308 subjects). Patients who received systemic therapy were classified as having severe psoriasis, whereas those who did not receive systemic therapy were classified as having mild psoriasis. The Cox proportional hazards regression analysis was conducted to estimate the association between psoriasis and HZ risk. Results: The overall incidence density rate of HZ in the psoriasis cohort than in the nonpsoriasis cohort (4.50 vs. 3.44 per 1,000 person-years), with a multivariable Cox proportional hazards model measured adjusted HR of 1.29 [95% confidence interval (CI) = 1.07–1.56]. In additional, compared with the nonpsoriasis cohort, the risk of HZ was higher in the severe psoriasis cohort than in the nonpsoriasis cohort (adjusted hazard ratio [HR], 1.61; 95% confidence interval [CI], 1.15–2.27). The comparison between psoriasis and nonpsoriasis cohorts revealed a greatest magnitude risk of HZ in women (adjusted HR, 1.36; 95% CI, 1.04–1.79), study participants in the age group of 20–39 years (adjusted HR, 1.77; 95% CI, 1.17–2.66), and study participants without any comorbidities (adjusted HR, 1.37; 95% CI, 1.02–1.84). Conclusions: Our results suggest that psoriasis is associated with an increased risk of HZ, which involves differences in sex and age. Although systemic therapy may have a major role in the risk of HZ, the intrinsic factors of psoriasis cannot be excluded.
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