Preliminary population-based incidence and prevalence estimates of systemic lupus erythematosus: the California Lupus Surveillance Project

Abstract

Background/Purpose: Previous estimates of prevalence and incidence of systemic lupus erythematosus (SLE) in the United States have varied widely. The California Lupus Surveillance Project (CLSP) is part of a national effort funded by the Centers for Disease Control and Prevention (CDC) to determine more credible estimates of incidence and prevalence of SLE, with a special focus on Hispanics and Asians. Method(s): The CLSP is a population-based registry designed to determine the incidence and prevalence of SLE in San Francisco County, California. Sources of cases included hospitals, rheumatologists, nephrologists, commercial laboratories, and state population databases. Over 15,000 potential SLE patients were identified after the initial queries, and trained abstractors performed detailed medical chart reviews on the>5,500 patients who met the catchment criteria of residence in San Francisco County within the years of 2007-2009. Cases were defined as patients with documentation of > 4/11 of the ACR Classification Criteria for SLE. Using SAS 9.3, we calculated prevalence and incidence rates and associated 95% confidence intervals (CI). Denominators for all rates were obtained from the U.S. Census data (revised 2000-2009 intercensal population files) for San Francisco County. Result(s): Preliminary overall crude prevalence and incidence of SLE in San Francisco County were 90.4/100,000 and 5.1/100,000 respectively. The highest prevalence of disease was observed in Black women (430.6/100,000), followed by Hispanic and Asian (163.8/100,000 and 158.9/100,000, respectively), and White (111.3/100,000) women (Table I). Conclusion(s): The CLSP uses more complete case finding methods to provide current estimates of prevalence and incidence in a racially and ethnically diverse population. Racial and ethnic disparities in SLE were confirmed with the highest burden of disease in Black women, followed by Hispanic and Asians, and, finally, White women. (Table Presented).