Background Data indicate that minority populations with systemic lupus erythematosus (SLE) are at higher risk of developing disease and have more severe outcomes, including mortality. However, whether specific causes of death vary by race and ethnicity has largely been unexplored, particularly for Asians and Hispanics.

Methods The California Lupus Surveillance Project identified potential SLE cases using community rheumatology and nephrology clinics, community hospitals, and integrated healthcare systems among individuals who were residents of San Francisco County, CA during January 1, 2007 – December 31, 2009. Cases were matched to the 2007-2017 National Death Index (NDI) data, which included the underlying cause of death for each individual. Chi-squared tests were used to examine differences in underlying cause of death by race (white, Black, Asian), ethnicity (Hispanic, non-Hispanic), and sex. Age-standardized mortality ratios (SMRs) between SLE patients and the general San Francisco county population were calculated for the leading cause of death, and estimated observed versus expected deaths by sex, race, and Hispanic/Latino ethnicity.

Results During the study period, 135 deaths related to SLE were identified (n=809). The top underlying cause of death overall (33%) and across all racial and ethnic groups was cardiovascular disease (CVD). Other top causes of death included rheumatic disease (18%) and hematological/oncological conditions (18%) overall, and across all racial groups. Analyses examining any cause of death indicated that rheumatic disease was more commonly indicated among white (50%) and Asian (46%) patients as compared to Black (27%) patients with SLE. In comparison to the general population of San Francisco County, CVD as the underlying cause of death was over three times higher among individuals with SLE (SMR=3.63) (table 1). CVD deaths for those with SLE were nearly three times higher for Black, approximately four times higher for Asian, and over six times higher for Hispanic/Latino individuals. CVD deaths were also elevated for females (SMR=4.7) and males (SMR=3.5) with SLE compared to the general population.

Conclusions Our results show that CVD is the leading underlying cause of death among SLE patients across various racial and ethnic groups, and that rheumatic disease may be less likely to be listed as a cause of death among Black patients with SLE. Further, Asian and Hispanic/Latino SLE patients experience a disproportionate burden of CVD mortality compared with the general population.

Acknowledgements This work was support by grants from the Lupus Foundation of America (TT) and the Rheumatology Research Foundation (TT).