Risk of serious infection and infection mortality in patients with psoriasis: A nationwide cohort study using the Taiwan National Health Insurance claims database

Background The risks of serious infections that lead to hospitalization and mortality in patients with psoriasis in Asia have not been comprehensively studied. Objectives We examined the incidence of serious infection and infection mortality in patients with psoriasis. Methods This population‐based retrospective cohort study used the Taiwan National Health Insurance claims database from 2000 to 2017. Adult patients with psoriasis were identified by a relevant International Classification of Diseases (ICD) code and matched to six comparators without psoriasis on age and sex. Psoriasis patients were categorized as having moderate‐to‐severe disease once exposed to systemic therapies, phototherapy or biologic therapies. The incidence of serious infection and infection mortality were identified by ICD codes from inpatient hospitalization and death registration. Cox proportional hazard models were used to compare the risk, and the results were adjusted for covariates and presented as adjusted hazard ratios (aHR) and 95% confidence interval (95% CI). Results Overall, 185,434 psoriasis patients and 1,112,581 comparators were included. A higher rate of serious infection (aHR: 1.21, 95% CI: 1.19–1.22) was found in patients with psoriasis compared to matched comparators without psoriasis, and the risk was enhanced when patients had moderate‐to‐severe psoriasis (aHR: 1.30, 95% CI: 1.27–1.34). Specifically, there was an increased risk of serious infection due to respiratory infections (aHR: 1.11, 95% CI: 1.09–1.13), skin/soft‐tissue infections (aHR: 1.57, 95% CI: 1.52–1.62), sepsis (aHR: 1.23, 95% CI: 1.19–1.27), urinary tract infections (aHR: 1.11, 95% CI: 1.08–1.14), hepatitis B (aHR: 1.18, 95% CI: 1.06–1.30) and hepatitis C (aHR: 1.49, 95% CI: 1.32–1.69). Furthermore, psoriasis patients were associated with a higher risk of infection‐related mortality (aHR: 1.15, 95% CI: 1.11–1.18) compared to matched comparators. Conclusion Patients with psoriasis had a higher risk of serious infection and infection mortality, which was enhanced by moderate‐to‐severe psoriasis. Practitioners should be aware of the increased risk in patients with psoriasis, but it should not be a barrier to offering effective treatment.