Epidemiology of isolated Cutaneous Lupus Erythematosus in the multiethnic population of Reunion Island (France): a retrospective multicentric study.

Abstract

Objective: Little data is available about the epidemiology of cutaneous lupus erythematosus (CLE) in South hemisphere and in multiethnic populations. We describe the prevalence and incidence of isolated CLE in the multiethnic population of Reunion Island (France), with its clinical characteristics.

Methods: The study was performed in the public hospitals and private dermatology practices of Reunion Island. Cases were identified through informatics databases. Cases were defined as isolated CLE, meaning they did not fulfill the criteria for Systemic Lupus Erythematosus (SLE). Incident cases were collected from 2008 to 2021. Prevalence was calculated on January the 1st 2022. A capture-recapture analysis was performed to estimate both prevalence and incidence.

Results: A total of 268 cases of CLE were identified and 218 were incident cases. The standardized prevalence of CLE was 43/100,000 persons and the average annual standardized incidence was 3.1/100,000 person-years. With a capture-recapture analysis, prevalence and annual incidence were estimated to be 99/100,000 persons [95%CI: 77.10-136.45] and 5.7/100,000 person-years [95%CI: 4.40-7.95] respectively. The mean age at diagnosis was 41.7 years old and female to male sex ratio of 4:1. Dark-skinned patients had a higher rate of discoid CLE and were more likely to receive immunosuppressants. Generalized discoid CLE, panniculitis and overlapping subtypes of CLE appeared as predictive markers of progression towards SLE.

Conclusion: The prevalence and incidence of CLE in the multiethnic population of Reunion Island seem higher than in light-skinned populations. We highlighted new risk factors of evolution towards SLE that should be known by practitioners to adjust follow-up.