Prevalence and incidence of systemic lupus erythematosus in a population-based registry of American Indian and Alaska Native people, 2007-2009

Objective: Few studies have investigated the epidemiology of systemic lupus erythematosus (SLE) in American Indian and Alaska Native (AI/AN) populations. The objective of this population-based registry was to determine the prevalence and incidence of SLE in the Indian Health Service (IHS) active clinical population in three regions of the US. Methods: For this population-based registry within the IHS, the denominator consisted of individuals: 1) in the IHS active clinical population in 2007, 2008, and/or 2009; and 2) residing in a community in one of three specified regions. Potential SLE cases were identified based on the presence of a diagnostic code for SLE or related disorder in the IHS National Data Warehouse. Detailed medical record abstraction was performed for each potential case. The primary case definition was documentation of four or more of the ACR classification criteria in the medical record. Prevalence was calculated for 2007, and mean annual incidence was calculated from 2007-2009. Results: The age-adjusted prevalence and incidence of SLE by the primary definition were 178 per 100,000 (95% CI 157-200) and 7.4 per 100,000 person-years (95% CI 5.1-10.4). In women, the age-adjusted prevalence was 271 (95% CI 238-307) and incidence was 10.4 (95% CI 6.6-14.6). The prevalence was highest in women aged 50-59 and in the Phoenix Area of IHS. Conclusion: The first population-based lupus registry in the US AI/AN population has demonstrated that the prevalence and incidence of SLE are high. Our estimates are as high as or higher than the rates reported in US black populations. © 2014 American College of Rheumatology.