Incidence and mortality of mucous membrane pemphigoid in France

BACKGROUND: Data on the incidence and mortality rates of mucous membrane pemphigoid (MMP) are limited and outdated. OBJECTIVES: To estimate the incidence and standardized mortality ratios (SMR) of MMP and identify prognostic factors for mortality. METHODS: We screened patients with MMP diagnosed in 20 dermatology departments in France between 2000 and 2021, using 3 national databases. The incidence rate was calculated based on the number of inhabitants in the corresponding administrative regions and patients' vital status was obtained from the French Institut national de la statistique et des études économiques (INSEE) death register. RESULTS: A total of 663 patients (376 women, 287 men) with a mean (SD) age of 70.57 (13.58) years was included. Annualized incidence rates progressively increased over the years, from 1.38 cases per million inhabitants per year in 2012 to a peak of 3.86 in 2019. The highest annualized incidence rate was observed in patients aged between 80 and 85 years [9.91 cases per million inhabitants per year; 95% confidence interval (CI) 6.43-15.28]. The 1-, 3- and 5-year SMRs were 1.00 (95% CI 0.73-1.33), 1.05 (95% CI 0.85-1.26) and 1.01 (95% CI 0.85-1.18), respectively. A higher SMR was observed in patients with ear, nose and throat (ENT) involvement (SMR 1.26, 95% CI 1.00-1.55). Predictors of mortality included age [hazard ratio (HR) 3.65 for ages 75-85 years vs. < 65 years (95% CI 1.67-7.99; P = 0.001) and 11.94 for ages > 85 years (95% CI 5.40-26.41; P < 0.001)], cancer (HR 2.66, 95% CI 1.75-4.06; P < 0.001) and diabetes (HR 1.80, 95% CI 1.17-2.77; P = 0.008). Patients with ocular-only involvement (HR 1.96, 95% CI 0.95-4.05; P = 0.07) and ENT involvement (HR 1.63, 95% CI 0.96-2.78; P = 0.07) had a trend towards a higher risk of mortality compared with oral forms of MMP. CONCLUSIONS: The incidence rate of MMP in France has more than doubled over the last decade. Ocular-only and ENT involvement are associated with a higher risk of mortality.