Background/Purpose: The CLSP is a population-based registry of individuals with SLE residing in San Francisco County, California from 2007 – 2009. The registry has a special focus on improving our understanding of SLE in Asian/Pacific Islander (PI) and Hispanic individuals, two groups previously understudied in population-based epidemiologic investigations. We used CLSP data to analyze differences in 1) lupus manifestations by sex and race/ethnicity and 2) time to development of these manifestations after disease onset.

Methods:   Relative risks (RR) of SLE manifestations were calculated using Poisson regression models adjusted for race/ethnicity, sex, age at SLE diagnosis, and duration of SLE disease. Kaplan-Meier and Cox proportional hazards methods were used to analyze time to development of severe manifestations of SLE, with higher hazard ratios (HR) indicating a shorter time to development of specific manifestations.

Results: 724 prevalent cases of SLE were identified with the following distribution by race/ethnicity: white (26.2%), Black (18.8%), Asian/PI (36.9%), Hispanic (15.5%), missing (2.6%). For lupus manifestations, Blacks, Asians/PIs, and Hispanics had increased prevalence of lupus nephritis relative to whites (RR 1.78, RR 1.74, and RR 1.46, respectively). Furthermore, Blacks had increased neurological manifestations (RR 1.50), Asians/PIs had increased mucocutaneous manifestations (RR 1.16), and both Blacks and Asians/PIs had increased hematologic manifestations (RR 1.08 and RR 1.07, respectively). For time to development of manifestations, statistically significant differences in lupus nephritis (p < 0.001), thrombocytopenia (p = 0.006), and neuropsychiatric abnormalities (p = 0.042) were observed by race/ethnicity, though this was not the case in the analysis of antiphospholipid (APS) (P = 0.092). Blacks, Asians/PIs, and Hispanics had earlier development (higher hazards) of lupus nephritis, thrombocytopenia, and APS relative to whites. Men had earlier development of lupus nephritis and thrombocytopenia relative to women (Table).

Conclusion: This analysis represents the first epidemiologic study comparing lupus manifestations among four major racial/ethnic groups and includes large numbers of Asians/PIs and Hispanics. We found 1) dramatic differences in the prevalence of several clinical SLE manifestations among race/ethnicities and 2) that Blacks, Asians/PIs, and Hispanics are at increased risk of developing many manifestations earlier than whites following initial SLE diagnosis. Men also developed lupus nephritis and thrombocytopenia earlier than women with SLE.