INCIDENCE AND DISTRIBUTION OF SUBEPIDERMAL AUTOIMMUNE BULLOUS SKIN DISEASES IN 3 FRENCH REGIONS

Background and Design: The incidence and distribution of autoimmune su bepidermal bullous diseases were estimated from prospective data (incl uding immunoelectron microscopy) obtained from 100 cases during a mean period of 35 months in three university dermatologic centers in Amien s, Limoges, and Tours, France, that correspond to a cumulative referen ce population of 3.55 X 10(6). Results: Using data from these regions, we found a mean annual incidence of autoimmune subepidermal bullous d iseases to be 10.4 per million people and, therefore, estimated the ov erall number of new cases of these disorders in France to be about 590 cases per year. According to clinical and immunoelectron microscopic criteria, a precise diagnosis was established in 94 cases, distributed as follows. bullous pemphigoid, 69 cases; cicatricial pemphigoid, 12 cases; linear IgA dermatosis, five cases; herpes gestationis, four cas es; epidermolysis bullosa acquisita, two cases; and vesiculobullous sy stemic lupus erythematosus, two cases. Conclusion: Our prospective stu dy is the first assessing the incidence and distribution of autoimmune subepidermal bullous disorders that systematically included immunoele ctron microscopic data. Our estimated incidence of bullous pemphigoid (seven new cases per million people per year) is large enough to estab lish bullous pemphigoid as the major autoimmune subepidermal bullous d isease for the purpose of therapeutic trials. On the contrary, all oth er disorders, particularly epidermolysis bullosa acquisita (estimated annual incidence, 0.17 to 0.26 per million people), were very rare and reflect the paucity of patients available for shortterm clinical stud ies in France.