SAN DIEGO – Blacks with systemic lupus erythematosus (SLE) who share the same social and geographic contexts as whites with the disease were disproportionately more likely to die young and to show severe patterns of mortality, according to a study of death certificate data.
“One of the most salient aspects of the epidemiology of lupus is the predilection of the disease for women and racial minorities,” lead study author Titilola Falasinnu, PhD, said at the annual meeting of the American College of Rheumatology.
Dr. Titilola Falasinnu
Dr. Falasinnu, a postdoctoral fellow in Stanford (Calif.) University’s department of health research and policy, and her associates examined SLE mortality across eight groups of race-county combinations published in 2006 and known as the “Eight Americas” (PLoS Med. 2006 Sep 12;3[9]:e260). This seminal work, which has been validated across multiple disease states, jointly characterized race, socioeconomic status, and geographical location in relation to health disparities in the United States to demonstrate the most important factors accounting for these disparities within the Eight Americas.
For the current analysis, Dr. Falasinnu and her associates were most interested in America 6 (black middle America), America 7 (Southern low-income rural blacks), and America 8 (high-risk urban blacks). “The question we wanted to ask is whether, on average, poorer individuals have more severe SLE mortality experiences, compared with richer individuals in the black community,” she said. “What happens when you hold race constant and you vary socioeconomic indices?” Using death certificate data from the National Center for Health Statistics Multiple Causes of Death database, they identified SLE-related deaths between 2003 and 2014. Next, they compared these data with mortality statistics from each of the Eight Americas.
In all, there were nearly 25,000 SLE-related deaths, of which 85% were female. More than one-third of deaths occurred among those aged 45-64 years, and the mean age at death was 57 years. More than half of deaths (64%) occurred among whites, and 31% among blacks. Among SLE decedents, northern rural whites in America 2 had the lowest mortality rates. Blacks in America 6, 7, and 8 had the highest mortality, yet there were no significant differences in the death rates among those three groups. “We found that in general, blacks were three times more likely to die with SLE, compared with those in America 3 [middle America],” Dr. Falasinnu said.
Asians, Native Americans, and blacks with SLE died at an average age of 48-49 years, regardless of their social context, while Northern whites had the highest life expectancy: an average age of 69 years. They also found that 17% of SLE deaths in America 2 occurred before the age of 50 years, compared with more than 50% in Americas 6, 7, and 8. The most frequently reported associated causes of death were cardiovascular disease (about 50% of all SLE-related deaths) and kidney manifestations (about 20% of all SLE-related deaths). Compared with those in America 3, racial minorities had a 23%-53% higher risk of infections, a 5%-64% higher risk of kidney disease, a 7%-23% lower risk of cardiovascular disease, and a 20%-52% lower risk of cancers.
“Although blacks inhabited three vastly different geographical and social contexts, SLE mortality parameters did not vary among socially advantaged and disadvantaged black Americas,” Dr. Falasinnu concluded. “Blacks sharing the same social and geographical contexts as whites were disproportionately more likely to die young and exhibit patterns of mortality associated with active SLE disease.”
She acknowledged certain limitations of the study, including that differences in the degree of underreporting on death certificates across racial groups could bias the results. “The Eight Americas framework does not allow for evaluation of ethnicity,” she added. “We were also unable to examine causes for the disparities in SLE mortality. One could argue that there are a lot of other social factors that are likely race related that are not necessarily captured by the Eight Americas. Also, as with most epidemiological studies, we cannot rule out the role that ecological fallacy may play where the population average may not be appropriate in estimating an individual’s risk of mortality.”
One of the study coauthors reported receiving partial salary support through the Dr. Elaine Lambert Lupus Foundation via the John and Marcia Goldman Foundation and previously receiving salary support through a lupus-related grant from the Genomics Institute of the Novartis Research Foundation. The other coauthors reported having no relevant disclosures.