Incidence of Auto-Immune Pemphigus in the Midi-Pyrénées Region in 2002–2006

Abstract

Introduction: Auto-immune pemphigus is an organ-specific immune disorder due to pathogenic auto-antibodies. Both genetic and environmental factors have been associated with the occurrence of auto-immune pemphigus. Little is known about the epidemiology of auto-immune pemphigus in western Europe. Objective: To evaluate the incidence of auto-immune pemphigus in south-western France (namely the Midi-Pyrénées region) in a 5-year period between 2002 and 2006. Materials and Methods: We performed a retrospective study of the annual incidence of auto-immune pemphigus diagnosed in the Midi-Pyrénées region, between January 1, 2002, and December 31, 2006. Possible cases of pemphigus were initially selected using skin direct immunofluorescence (DIF) databases from all laboratories in the Midi-Pyrénées region. Systematic validation of all cases was performed by two of the authors (N.M., M.T.). To qualify as a case of auto-immune pemphigus, patients had to fulfil the following criteria: history of clinical signs of pemphigus as assessed by a dermatologist and a positive DIF. To be included in the study, validated cases of auto-immune pemphigus had to fulfil the following criteria: the date of first positive skin DIF between January 1, 2002, and December 31, 2006, and patient living in the Midi-Pyrénées region at the time of the first positive skin DIF. Results: Between 2002 and 2006, 91 patients with positive DIF were identified. Fifty-four patients with positive DIF did not meet the validation criteria for the study. Thirty-seven cases were included in the analysis. The crude annual mean incidence of auto-immune pemphigus between 2002 and 2006 was 2.7 cases/10⁶ inhabitants/year (95% CI: 1.87–3.69). The world-population-standardized annual mean incidence of auto-immune pemphigus was 1.55 (95% CI: 0.99–2.11). Conclusion: We report a 1.55/10⁶ inhabitants/year world-population-standardized incidence of auto-immune pemphigus in the south-west of France. A nationwide epidemiological study of pemphigus should be performed in France.