Global Incidence and Prevalence of Bullous Pemphigoid: A Systematic Review and Meta-Analysis

Abstract

Background: Bullous pemphigoid (BP) is the most common autoimmune blistering disease. Although there have been some studies on the epidemiology of BP in different regions, global estimates of the incidence and prevalence of BP are still lacking. Methods: A systematic review of population-based studies as well as outpatient and inpatient studies reporting the incidence and (or) prevalence of BP was performed. The Medline, EMBASE and Cochrane Library databases were searched from their inception to September 1, 2019. Quantitative studies investigating the incidence and prevalence of BP were included. Quality assessment was performed with a tool designed to provide a critical appraisal of prevalence or incidence studies. We investigated the incidence and prevalence of BP stratified by continent, age, sex and diagnostic method. Between-study heterogeneity was assessed using the I2 statistic. Findings: In the 35 included studies, 143,005,387 individuals from 23 countries were examined; 22 (62.9%) studies from 17 countries reported the incidence (n=51,849,277) and 15 studies from 14 countries (42·9%) reported the prevalence (n= 93,895,512). Two (5·7%) studies mentioned both the incidence and the prevalence. We found that the overall incidence of BP was 0·1138 per 10,000 person-years (95% CI: 0·0631–0·1341). the specific prevalence values were 0·2397 (95% CI: 0·1972-0·2849), 0·1444 (95% CI: 0·0879-0·2122), 0·082 (95% CI: 0·0197-0·1814) and 0·0342 (95% CI: 0·0254-0·0443) per 10,000 person-years in North America, Europe, Asia, and Africa, respectively; the incidence values for males and females were 0·0172 (95% CI: 0·0075-0·0396) and 0·01334 (95% CI: 0·0048-0·0221) per 10,000 person-years, respectively; and the incidence values among the age groups of 80+, 70-79 and 60-69 years old were 0·1913 (95% CI: 0·0811-0·3344), 0·1154 (95% CI: 0·0894-0·1443) and 0·0313 (95% CI: 0·02-0·0449) per 10,000 person-years, respectively. With regard to the different diagnostic methods, the incidence values were 0·1610 (95% CI: 0·0666-0·2863), 0·091 (95% CI: 0·0122-0·2318), 0·0540 (95% CI: 0·0041-0·1552), and 0·0471 (95% CI: 0·0094-0·1113) per 10,000 person-years for “typical clinical features + histopathology + direct immunofluorescence + serological test”, “typical clinical features + direct immunofluorescence + serological test”, “typical clinical features + serological test” and “typical clinical features + histopathology + serological test”, respectively. For the population-based prevalence, the pooled value was 0·02% (95% CI: 0·001-0·19). For the clinic-based prevalence, the pooled value was 0·11% (95% CI: 0·03-0·43). Interpretation: This study estimated the global incidence and prevalence of BP with respect to its spatial and population distributions. The overall estimate of the pooled incidence of BP was 0·1138 per 10,000 person-years. A higher incidence of BP was found in North America, among females and among older people. The pooled population-based and clinic-based prevalence estimates were 0·02% and 0·11%, respectively. The findings should be cautiously interpreted due to the high degree of heterogeneity among the included studies. Funding Statement: The First-class Discipline Construction Foundation of Guangzhou University of Chinese Medicine (Chinese medicine department), the Young Top Talent Project of Scientific and Technological Innovation in Special Support Plan for Training High-level Talents in Guangdong (No. 2017TQ04R627) and the Youth Research and Cultivation Project of Guangzhou University of Chinese Medicine (No. 2019QNPY02). Declaration of Interests: The authors declare that they have no conflicts of interest. Ethics Approval Statement: PRISMA was utilized for this study.