Increased risk of psoriasis following scabies infection: A nationwide population-based matched-cohort study

Both scabies and psoriasis are pruritic inflammatory skin diseases. The clinical manifestations are similar and provocation of psoriasis by mite bite was reported. The association between scabies and psoriasis was not investigated before. We conducted this nationwide population-based matched-cohort study to describe if patients with a diagnosis of scabies have a different risk of developing new psoriasis. From the National Health Insurance Research Database of Taiwan, patients with scabies (n = 5137) were identified and matched for age and sex with non-scabies controls (n = 19 142). We tracked them for a 7-year period to identify the incidence of psoriasis. One hundred and ninety (0.8%) patients with newly diagnosed psoriasis were identified; 91 (1.8%) from the scabies group and 99 (0.5%) from the control group. Patients with scabies had a higher risk of subsequent psoriasis, with a crude hazard ratio of 3.45 and an adjusted hazard ratio (aHR) of 3.03 (95% confidence interval, 2.24-4.11). An increased risk for psoriasis among patients with scabies was observed (aHR, 3.03). Immunopathology involving the T-helper 17 cell-mediated inflammatory pathway may contribute to this association. Physicians may consider implementing assessments of psoriatic symptoms in patients with scabies.