medwireNews: An analysis of all deaths recorded over a 46-year period in the USA shows that mortality rates attributable to systemic lupus erythematosus (SLE) have decreased since the 1960s, but remain high relative to rates of death from other causes.
As reported in the Annals of Internal Medicine, the researchers identified 50,249 deaths attributable to SLE and 100,851,288 non-SLE deaths that occurred between 1968 and 2013.
The age-standardized SLE mortality rate decreased from 0.45 per 100,000 persons to 0.34 per 100,000 persons over the study period, translating into a 24.4% relative decline. However, this reduction in SLE-related mortality was lower than that for non-SLE mortality rates, which decreased from 1303.1 to 731.6 per 100,000 persons, a 43.9% relative decrease.
And non-SLE mortality rates decreased every year since 1968, whereas death rates attributable to SLE decreased until 1975, then increased between 1975 and 1999, and declined thereafter.
In subgroup analyses, age-standardized SLE mortality rates were lower in 2013 relative to 1968 among both sexes, in all geographic regions, and among Black and White people. However, women experienced a smaller relative reduction in SLE mortality rates than men (21.4 vs 47.4%), as did Black people relative to White people (13.3 vs 33.3%), and those living in the South compared with other geographic regions (7.0 vs 32.5–40.4%).
When the authors carried out a multiple logistic regression analysis adjusting for potentially confounding factors, women had a greater than fivefold increased risk for SLE mortality than men between 1999 and 2013, while people of racial or ethnic minorities had a significantly higher risk than White participants, and people living in the South or West had a greater risk than residents of the Northeast.
Furthermore, interaction testing indicated that there were significant interactions between race/ethnicity and sex or geographic region, meaning that “race/ethnicity modified the relationship among sex, geographic region, and SLE mortality,” explain Ram Singh (University of California, Los Angeles, USA) and fellow researchers.
Taken together, these findings reveal that “[d]espite improving trends, SLE mortality remains high relative to non-SLE mortality, and disparities persist between subpopulations and geographic regions,” they write.
However, the researchers acknowledge that under-reporting of SLE on death certificates “may result in underestimates of SLE mortality in certain subpopulations,” and that changes in recording SLE-related deaths over time “could have influenced SLE mortality trend estimates.”
Looking to the future, Singh and colleagues call for “[c]omprehensive examination of SLE mortality using prospective population-based data collection” in order to understand the mechanisms underlying the observed disparities and identify “potentially modifiable risk factors that might inform targeted research and public health programs to promote health equity across subpopulations and regions of the United States.”
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