Background In a multiethnic U.S cohort compared to White patients., Black patients developed systemic lupus erythematosus (SLE) at a younger age, had more severe disease, and had worse outcomes. Patients of Asian ancestry developed SLE were similar but also had more frequent autoantibodies. Black and Asian SLE patients have not been directly compared across nations.

Methods The Georgia Lupus Registry (GLR) is a population-based registry of validated SLE patients in Atlanta of those with ≥4 ACR criteria or 3 ACR criteria with a final diagnosis of SLE by a rheumatologist. The Hanyang BAE Cohort is comprised of SLE patients meeting ACR and/or SLICC criteria from a single center. A total of 248 Black patients from 2002–04 (GLR) and 395 Korean patients from 2002–13 (BAE) with incident disease (<1 year) were compared. The outcomes of end-stage renal disease (ESRD) and mortality were evaluated for cumulative incidence over time and by multivariable Cox proportional hazard regression. Causes of death were derived from national databases.

Results A total of 248 U.S. Black patients were compared with 395 Korean patients. The cause-specific hazard ratio (GLR vs. BAE), adjusted by age of SLE onset, sex, and total number of ACR criteria, was 6.42 (2.40–17.16) for ESRD and 2.7 (1.40–5.21) for mortality. The most frequent causes of death in the U.S. Black population were SLE (33%), other (29.5%, of which 42.3% were neoplasms), and cerebrovascular disease (23.9%). In the Korean population, it was SLE (57.1%), infection (21.4%), and others (14.3%).

Conclusions U.S. Black and Korean SLE patients showed significant differences clinically in the first year of disease. Despite similar frequencies of renal involvement at baseline, there was a notable over six-fold increased risk in U.S. Black patients to progress to ESRD. These comparisons and contrasts are opportunities to better explore biological as well environmental differences in disease expression and outcomes.