Background Bullous pemphigoid (BP) has been associated with neurological and psychiatric diseases; however, large-scale population-based study of different comorbid diseases in patients with BP is quite limited.
Objectives We sought to analyse the prevalence of neurological, psychiatric, autoimmune and inflammatory skin diseases prior to the diagnosis of BP and their associations with BP among patients with BP from a nationwide database in Taiwan.
Methods A total of 3485 patients with BP and 17 425 matching controls were identified from the National Health Insurance Database in Taiwan from 1997 to 2008. Conditional logistic regression analyses for a nested case–control study were performed to examine the prevalence of comorbidities prior to the diagnosis of BP between these two groups.
Results Overall, our results showed that stroke [odds ratio (OR) 3·30; 95% confidence interval (95% CI) 3·03–3·60], dementia (OR 4·81; 95% CI 4·26–5·42), Parkinson disease (OR 3·49; 95% CI 3·05–3·98), epilepsy (OR 3·97; 95% CI 3·28–4·81), schizophrenia (OR 2·56; 95% CI 1·52–4·30) and psoriasis (OR 2·02; 95% CI 1·54–2·66) were significantly associated with BP. Among them, the association with schizophrenia and psoriasis was predominant in female and male patients, respectively, with BP. It remains for all these comorbid diseases to be independently associated with BP by multivariate analysis.
Conclusions Patients with BP are more likely to have various neurological diseases, schizophrenia and psoriasis prior to the diagnosis of BP, supporting associations found in other studies. Further research is required to elucidate the tentative causal association with BP.