Increased Risk of Bullous Pemphigoid after First-Ever Stroke: A Population-Based Study

Background: We hypothesize that autoantibodies are induced after the blood-brain barrier is damaged by stroke and the risk of bullous pemphigoid (BP) is increased after stroke. We assess the risk of BP after first-ever stroke in a nationwide population-based cohort of first-ever stroke patients. Methods: We extracted data from the Longitudinal Health Insurance Database 2005 and identified patients with first-ever stroke as well as control patients matched for age, gender, and year of enrollment. The risk of BP in first-ever stroke patients in comparison with that in control patients was analyzed using Cox regression. Results: Of 12,607 patients with first-ever stroke, 38 (0.3%) patients developed BP in a median of 3.5 years. In the control patients, 8 persons (0.06%) had BP in a median of 3.7 years. The crude hazard ratio (HR) of BP in first-ever stroke patients was 4.83 (95% CI 2.25-10.34, p < 0.001) compared to the control group. The adjusted HR was 4.20 (95% CI 1.94-9.08, p < 0.001) after adjustments for age, gender, hypertension, diabetes, dementia, epilepsy, Parkinson disease, furosemide, and neuroleptics for stroke patients. Conclusions: The risk of BP is increased in first-ever stroke patients in a nationwide population-based cohort and this association is independent of well-known confounders of BP.