ACR 2017 | Daily Highlights
Unraveling Race and Social Context in Understanding Disparities in Lupus Mortality in the United States
Authors: Titilola Falasinnu1, Yashaar Chaichian2, Latha Palaniappan3 and Julia F Simard4, 1Health Research and Policy, Stanford University, Stanford, CA, 2Medicine, Immunology & Rheumatology Division, Stanford School of Medicine, Stanford, CA, 3Stanford University Medical Center, General Medical Disciplines, Stanford, CA, 4Division of Epidemiology, Health Research and Policy Department, Stanford School of Medicine, Stanford, CA
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that is a source of significantly decreased life expectancy in the United States. Women and racial/ethnic minorities account for an increasingly disproportionate number of cases, with genetic factors regarded as potentially causative. The role of social and environment contexts has received little attention. We examined SLE mortality rates across eight groups of race-county combinations of the US population, developed by Murray et al in 2006, that are referred to as the “Eight Americas”. We examined SLE mortality in the Eight Americas over time to assess whether the impact of race is attenuated when the social and geographic context is also considered. We also examined whether age at death in SLE decedents differs across the Eight Americas, and explicated patterns of disease comorbidities among SLE decedents in the Eight Americas.
Using death certificate data from the National Center for Health Statistics Multiple Cause of Death (MCOD) database, SLE-related deaths were identified via International Classification of Diseases, 10th revision (ICD-10) codes: M32.1, M32.9, and M32.8. Annual SLE-related mortality rates and mortality rate ratios were calculated for each of the Eight Americas using America 3 as the reference category. Average Annual Percent Change (AAPC) in mortality rates summarized trends over a fixed predetermined interval. To examine trends in associated causes of death listed in the death certificates of SLE decedents, we calculated Proportionate Mortality Ratios (PMRs) for the top causes of death (derived from the literature) among SLE patients. Statistical analyses were performed using SAS version 9.4.
There were 24,773 SLE-related deaths between 2003 and 2014. Mortality was highest among blacks in three race-geographical contexts (Americas 6, 7, & 8). Age at death was lowest (~48 years) for blacks and Asians, regardless of geographical context, and highest among low-income rural whites (~65 years). Blacks and Asians were also more likely to have infectious diseases listed as associated causes of death, a finding consistent across geographical contexts, while whites were more likely to have cardiovascular diseases and neoplasms reported as associated causes of death.
Blacks sharing the same social and geographical contexts as whites were disproportionately more likely to die young and exhibit severe patterns of mortality. Although blacks inhabited three vastly different geographical and social contexts, SLE mortality parameters did not vary among socially advantaged and disadvantaged blacks. Together, these findings suggest that race may transcend social and geographical parameters as a key determinant of SLE mortality.
T. Falasinnu, None; Y. Chaichian, None; L. Palaniappan, None; J. F. Simard, None.
The ethnic component of connective tissue diseases and SLE in particular is known for long time. However, it has been technically extremely challenging to identify, in how far these ethnic differences are driven by social and environmental context on the one hand and ethnic/genetic differences on the other hand. The current study uses an extremely large database with more than 24000 SLE-related deaths from the US and was thus able to produce robust results in mortality rates of different races with different social and environmental context. The results convincingly show that in Afro-Americans with the same social and environmental/geographical context as whites, mortality remains to be higher due to their ethnic background. This, in general, supports the concept that ethnic background rather environmental factors such as social or geographical context is a major driver of disease severity at least in SLE patients.
Prof. Dr. Oliver Distler