Background/Purpose: Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease with manifestations that vary widely in severity. Contemporary data indicate that minority populations are at higher risk of developing SLE and have more severe outcomes. However, population-based estimates of mortality by race and ethnicity are lacking, 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.  SLE cases were defined as using American College of Rheumatology Classification Criteria (≥4 of the 11 revised criteria as defined in 1982 and updated in 1997) or two alternative definitions: SLE diagnosed by the patient’s treating rheumatologist plus 3 ACR criteria; or lupus-related kidney disease (World Health Organization class II-VI lupus nephritis upon biopsy or documented record of SLE diagnosis and dialysis or renal transplantation). Cases were matched to the 2007-2017 National Death Index (NDI) data to measure SLE mortality by age, sex, race and ethnicity. Multivariable risk ratios estimated the association between race and Hispanic/Latino ethnicity with mortality, adjusting for age, sex and years since diagnosis. Standardized mortality ratios (SMRs) estimated observed versus expected deaths by age group, sex, race and Hispanic/Latino ethnicity.

Results: Of the 812 SLE cases analyzed, 90% were female; 38% were white, 20% black, 36% Asian, and 5% mixed/other race; and 17% were Hispanic/Latino. 135 deaths (16.6%) were identified. Mean age at diagnosis among all SLE cases was 34.9 (±15.9) years, and mean age at death was 62.0 (±15.8) years. Mortality increased with older age; among racial/ethnic groups, blacks had the highest percent mortality (25.0%) and a significantly increased risk of mortality after adjusting for age group, sex, ethnicity and disease duration (Table 1). There were no differences in mortality by sex or Hispanic/Latino ethnicity. On average, black individuals died 6.8 years earlier than whites; individuals of Hispanic/Latino ethnicity died 9.5 years earlier than non-Hispanic/Latinos.

Overall, SMRs were three times higher among SLE cases than in the general population of San Francisco County (Table 2). SMRs for those with SLE were four times higher for females, Asians and Hispanic/Latinos, three times higher for males, and two times higher for whites and blacks compared with their non-SLE counterparts. Among females, SMRs were exceptionally high for Asians (4.1) and Hispanic/Latinas (5.8).

Conclusion: These findings provide the first population-based estimates of mortality among Asians and Hispanic/Latinos with SLE and suggest that public health programs and clinical practices targeting the health and maintenance of low disease activity within these populations are needed to reduce mortality.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

CI = Confidence Interval * Population estimates by age group, sex, race, and ethnicity for San Francisco County from 2007-2017 were obtained from the CDC Wonder database (https://wonder.cdc.gov): Centers for Disease Control and Prevention, National Center for Health Statistics. Underlying Cause of Death 1999-2018 on CDC WONDER Online Database, released in 2020. Data are from the Multiple Cause of Death Files, 1999-2018, as compiled from data provided by the 57 vital statistics jurisdictions through the Vital Statistics Cooperative Program. Accessed at http://wonder.cdc.gov/ucd-icd10.html on Mar 21, 2020 6:24:20 PM † Risk ratios estimated using a multivariable Poisson model that modeled sex, age category, race (white, black, Asian, other), ethnicity (non-Hispanic/Latino, Hispanic/Latino) simultaneously, adjusting for years since diagnosis. A total of 104 cases were excluded from the multivariable model: 19 cases were missing race information, including two who died, and 85 cases were missing Hispanic/Latino ethnicity status, including four who died. § Hispanic/Latino ethnicity is considered a distinct concept from race, therefore it was collected and reported separately from race.

CI = Confidence Interval * The standardized mortality ratio is a ratio between the observed number of deaths in those with SLE and the number of deaths expected, based on age groups defined in the CDC Wonder Database. Sex, race and Hispanic/Latino ethnicity specific rates in San Francisco County were used, depending on the particular characteristic examined. CIs are calculated for each estimated SMR by assuming a Poisson process. †Age in 2008 was used for adjustment. §Forty-one cases were excluded from race-specific analyses, including four who died: 22 cases had missing race information and 19 cases identified as a race other than white, black or Asian, for which estimates are not available through the CDC Wonder Database. ¶Eighty-five cases who were missing Hispanic/Latino ethnicity status, including four who died, were excluded from ethnicity-specific estimates. ** For female-specific race and ethnicity analyses, crude rates for age group < 15 years were not provided by the CDC Wonder Database or were unreliable and therefore not included in calculations; there was insufficient sample size to generate specific race/ethnic estimates for men.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-among-minority-populations-with-systemic-lupus-erythematosus-including-asian-and-hispanic-status-the-california-lupus-surveillance-project-2007-2017/