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Background Data on the incidence and mortality rates of mucous membrane pemphigoid (MMP) are limited and outdated.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 This study aimed 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 to 2021, using the French national database of rare diseases. The incidence rate was calculated based on the number of inhabitants in the corresponding administrative regions and patients’ vital status was obtained from the national institute of demography (INSEE) death register. Results A total of 663 patients (376 women, 287 men) with a mean age of 70.57 ± 13.58 years were included. Annualized incidence rates progressively increased over the years, from 1.38 cases/million inhabitants/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/million inhabitants/year; 95% CI =6.43 to 15.28). The 1-, 3- and 5-year SMRs were 1.00 (95% CI = 0.73 to 1.33), 1.05 (95% CI = 0.85 to 1.26), and 1.01 (95% CI = 0.85 to 1.18), respectively. A higher SMR was observed in patients with ear, nose, and throat (ENT) involvement (SMR=1.26, 95% CI = 1.00 to 1.55). Predictors of mortality included age (Hazard ratio [HR]=3.65 for ages 75-85 years vs <65 years, 95% CI =1.67 to 7.99; p=0.001, and HR=11.94 for ages >85 years, 95% CI =5.40 to 26.41; p<0.0001), cancer (HR=2.66, 95% CI = 1.75 to 4.06; p<0.0001), and diabetes (HR=1.80, 95% CI = 1.17 to 2.77; p=0.008). Patients with ocular-only involvement (HR=1.96, 95% CI = 0.95 to 4.05; p=0.07) and ENT involvement (HR=1.63, 95% CI = 0.96 to 2.78; p=0.07) had a trend towards a higher risk of mortality compared with oral ± skin forms of MMP. Conclusions The incidence rate of MMP in France has more than doubled over the last decade. Ocular-only and ENT involvement were associated with a higher risk of mortality.