Increased risk of pemphigoid following scabies: a population-based matched-cohort study.

BACKGROUND: No prior study has investigated the possibility that scabies patients may be at an increased risk for developing pemphigoid.

OBJECTIVE: To evaluate the risk of pemphigoid following scabies during a 3-year follow-up period using a Taiwanese population-based claims database and taking clinical and demographic characteristics into consideration.

METHODS: This investigation consisted of a study group of 6793 subjects with a diagnosis of scabies and 33 965 randomly selected subjects used as a comparison group. Each patient was tracked for 3 years following their index dates to identify those who received a subsequent diagnosis of pemphigoid. Stratified Cox proportional hazards regressions were used to compute the hazard ratio (HR) of pemphigoid during the 3-year follow-up period.

RESULTS: Of the 40 758 subjects, 52 (0.13%) had received a diagnosis of pemphigoid during the 3-year follow-up period; 33 (0.49% of the study group) were from the study group and 19 (0.06% of the comparison group) were from the comparison group. Compared to subjects without scabies, the HR for pemphigoid for subjects with scabies was 5.93 within the 3-year follow-up period following the index date after adjusting for monthly income, hypertension, diabetes, obesity, psoriasis, stroke, dementia, Parkinson's disease, coronary heart disease, schizophrenia or bipolar disorder, and after censoring those that died during the follow-up period.

CONCLUSIONS: This study detected an increased risk for pemphigoid among patients suffering from scabies. Physicians treating elderly patients with a history of scabies should be alert to the development of pemphigoid.