Risk factors for bullous pemphigoid in the elderly: a prospective case-control study

A rise in the incidence of bullous pemphigoid (BP) was documented recently in Europe, and the main risk factors for BP remain unknown. We conducted a multicenter case-control study to evaluate risk factors for BP. We identified 201 incident BP cases and 345 controls individually matched for age, gender, center, and place of residence (home, nursing home, or extended-care facility). We used univariate and multivariate logistic regression analyses to compare drugs used for over 3 months, comorbidities, and physical and cognitive impairments between cases and controls. Mean age of BP patients was 84.2 (±8.7) years. Factors independently associated with BP by multivariate analysis were major cognitive impairment (odds ratio (OR), 2.19; 95% confidence interval (95% CI), 1.24-3.87), bedridden condition (OR, 2.19; 95% CI, 1.23-3.89), Parkinson's disease (OR, 2.16; 95% CI, 1.09-4.27), unipolar or bipolar disorder (OR, 5.25; 95% CI, 1.21-22.86), and chronic use of spironolactone (OR, 2.30; 95% CI, 1.20-4.46) or phenothiazines with aliphatic side chains (OR, 3.70; 95% CI, 1.21-11.34). Chronic analgesic use was associated with a lower risk of BP (OR, 0.49; 95% CI, 0.30-0.81). Thus, risk factors for BP include neurological disorders, particularly dementia and Parkinson's disease, psychiatric disorders (unipolar and bipolar disorders), bedridden condition, and chronic use of several drugs.