Bullous pemphigoid and its association with neurological diseases: a systematic review and meta-analysis

Bullous pemphigoid (BP) is a chronic, autoimmune vesiculobullous disease that frequently occurs in the elderly population. Previous epidemiological studies have suggested an association between BP and neurological diseases; some studies, however, showed conflicting results. This study aimed to investigate if patients with BP have significantly higher risks for neurological disorders, compared to controls. A comprehensive search was performed using MEDLINE, EMBASE and Cochrane library databases. Case-control and cohort studies that assessed the relationship between BP and neurological diseases were included. DerSimonian and Laird random-effects models were utilized to calculate the pooled relative risks (RRs). Publication bias was evaluated qualitatively by constructing a funnel plot and quantitatively by conducting Egger's test. Fourteen studies, with 23 369 BP cases and 128 697 controls were included in this meta-analysis. Patients with BP were significantly more likely to have stroke (RR 2.68, 95% CI: 2.07-3.46), Parkinson's disease (PD; RR 3.42, 95% CI: 3.01-3.87), dementia (RR 4.46, 95% CI: 3.23-6.16), epilepsy (RR 2.98, 95% CI: 1.42-6.28), multiple sclerosis (RR 12.40, 95% CI: 6.64-23.17) and any aforementioned neurological disease (RR 4.93, 95% CI: 3.62-6.70), compared to controls. Moderate to high heterogeneity were observed for analyses of most neurological diseases, except for PD and multiple sclerosis. This study provided support for a significant association between BP and neurological diseases. Clinicians should be aware of this association and manage modifiable risk factors for neurological diseases accordingly.