Bullous pemphigoid and antecedent neurological diseases: An association with dementia

Background: Bullous pemphigoid is the most common subepidermal immunobullous disorder. Studies have reported the association between bullous pemphigoid and various neurological diseases. Aims: The aim of this study was to evaluate whether bullous pemphigoid is associated with pre-existent neurological diseases and whether specific diseases exhibit this association. Methods: All dermatology inpatients from January 2010 to May 2015 were analyzed. Bullous pemphigoid cases were identified based on clinical features and consistent histopathologic and direct immunofluorescence findings. Patients with other autoimmune bullous skin disorders were excluded. An equal number of inpatients with other skin conditions were selected randomly as age-and sex-matched controls. Results: Out of 3015 inpatients, 103 cases of bullous pemphigoid and 103 age-and sex-matched controls were included. Seventy six patients with bullous pemphigoid had a history of at least one neurological disease. After adjusting for age, gender, race, functional status and neuro-psychiatric medications, patients with bullous pemphigoid were found to be approximately thrice as likely to have a history of at least one neurological disease than were controls (odds ratio: 2.88; 95% confidence interval: 1.32-6.26; P = 0.008). Amongst the pre-existing neurological diseases, only dementia was statistically more prevalent in bullous pemphigoid cases compared to controls (adjusted odds ratio: 2.61; 95% confidence interval: 1.19-5.75; P = 0.017). Parkinson disease and psychiatric disorders demonstrated a higher adjusted risk among bullous pemphigoid patients but the difference was not statistically significant. Limitations: The limitations were potential referral and selection bias, as the patients were inpatients. There is a possible misclassification as the diagnosis of neurological diseases was performed using medical records. The duration from the diagnosis of neurological diseases to bullous pemphigoid could not be accurately determined as it was a retrospective review of records and most neurological diseases have a prolonged course. Conclusions: Pre-existent neurological disease, specifically dementia, was found to be associated with bullous pemphigoid.