A nationwide, population-based, matched-cohort study conducted in Taiwan and published in The Journal of Dermatology presented evidence that suggests a possible association between scabies infections and an increased risk for psoriasis.

A total of 5137 patients with scabies were identified from the National Health Insurance Research Database of Taiwan and matched according to age and gender with 19,142 controls without scabies. All participants were followed for 7 years to study the incidence of psoriasis.

Overall, of the 24,279 participants, 190 were newly diagnosed with psoriasis during the 7-year follow-up, including 1.8% (91 of 5137) of patients from the scabies group and 0.5% (99 of 19,142) of patients from the control group.

There was a significantly increased risk for psoriasis in patients with a scabies infection vs controls without scabies (crude hazard ratio [HR] 3.45; 95% CI, 2.60-4.59; P <.001).

After adjusting for such potential covariates as sex, income, and comorbidities, participants in the scabies group continued to exhibit a higher risk for psoriasis, with an adjusted HR of 3.03 (95% CI, 2.24-4.11) compared with patients in the control group.

The researchers suspected that the immunopathology involving the T-helper 17 cell-mediated inflammatory pathway might be responsible for this association. Of note, older patients had a lower risk for psoriasis compared with younger patients, but the difference was not statistically significant.

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The investigators concluded that clinicians should consider implementing assessments of psoriatic symptoms in the long-term follow-up of patients with a scabies infection. Early and aggressive treatment of a scabies infection might help decrease a patient’s subsequent risk for psoriasis.

Reference

Liu J-M, Lin C-Y, Chang F-W, Liu Y-P, Liang C-P, Hsu R-J. Increased risk of psoriasis following scabies infection: a nationwide population-based matched-cohort study [published online January 21, 2018]. J Dermatol. doi:10.1111/1346-8138.14221