Background/Purpose: Systemic lupus erythematosus (SLE) is not well characterized among Asian Americans, particularly among subgroups of Asians. We aim to compare measures of disease status, including severity, damage, activity, and physical functioning, by race/ethnicity in a diverse SLE cohort.

Methods: Data were derived from the California Lupus Epidemiology Study (CLUES), a population based, multi-ethnic cohort of SLE patients in the San Francisco area begun in 2015. SLE was defined according to the 1997 ACR criteria. At baseline, participants had a physician exam that included the SELENA- SLE Disease Activity Index (SLEDAI) and SLICC/ACR Damage Index (SDI). The Lupus Severity Index (LSI) was computed based on the ACR criteria confirmed at the study visit. The LSI assigns a weighted value to each criterion and is scaled 0-10; it has been shown to correlate with disease activity and mortality. Patients completed the SF-36 Physical Functioning (PF) subscale; this scale has a potential range of 0-100, with higher values indicating better function. They also provided self-identified race/ethnicity and details of Asian origin. We compared SLE status measures by race/ethnicity and within subgroups of Asian origin, in regression models controlling for age, disease duration, income < 125% of the federal poverty limit, and gender. Tukey post hoc tests were used to compare the outcomes among Asian subgroups.

Results: Among 283 patients, 30% were white, 20% Latino, 11% African American, and 39% Asians. The 102 Asian Americans included 62 Chinese, 23 Filipino and 17 from all other subgroups. Nearly 90% of the cohort were women, with mean age 45±14 and mean disease duration of 16±10 years. Just over half the cohort had some damage (SDI> 0) at baseline. Overall means and distributions of the status measures are shown in the table, along with results from the regression models. Asian Americans in all subgroups had significantly higher LSI scores than whites, as did Latinos and African Americans. However, Asians did not differ from whites in SLICC, SLEDAI or SF-36 PF. Comparing outcomes among the Asian subgroups, the only significant differences were in the SF-36 PF scores, for which Chinese patients had less impairment (mean 48.0) compared to Filipinos (mean 42.1, p=0.02) or other Asians (mean 42.3, p=0.04).

Conclusion: In this multi-ethnic cohort, Asians had high disease severity, similar to African Americans and Latinos, but accumulated significantly less damage than these other racial/ethnic groups over time.  The social, environmental, biological or health factors leading to this paradox among Asians requires further investigation. With the exception of physical functioning, there were few differences between the Asian subgroups, but this analysis was limited by small sample size and should be further explored as the cohort expands.