US study identifies racial disparities in lupus nephritis mortality
medwireNews: Lupus nephritis mortality rates have increased in recent years and are significantly higher among Black people than among those of other races or ethnicities, US study data show.
The findings, presented by Ram Raj Singh (University of California, Los Angeles, USA) at the ACR Convergence 2021 virtual meeting, also revealed that that where a person lives can modify the impact that their race or ethnicity has on lupus nephritis mortality risk.
Using the US Center for Disease Control’s WONDER database, Singh and colleagues identified 8899 deaths attributed to lupus nephritis and 25,973 deaths due to systemic lupus erythematosus (SLE) between 1999 and 2019.
During this period, the lupus nephritis age-standardized mortality rate (ASMR) decreased by 27.2% from 0.176 per 100,000 in 1999 (501 deaths) to 0.128 per 100,000 in 2019 (438 deaths).
It was not a continuous decrease, however. Indeed, trend analysis showed that lupus nephritis ASMR decreased significantly from 1999 to 2009, plateaued between 2009 and 2012, decreased again from 2012 to 2015, but then increased significantly between 2015 and 2019.
Conversely, the ASMR for all SLE decreased constantly throughout the observation period, which suggests “it is unlikely that increased awareness or even reporting of SLE has resulted in an increase in lupus nephritis mortality in the last 4 or 5 years,” said Singh.
When the researchers looked at the data by race, they observed that the lupus nephritis ASMR was a significant six times higher in Black people than in White people, at approximately 0.43 versus 0.07 deaths per 100,000, respectively. It was also more than double the approximate ASMR observed in American Indian or Alaska Native people (0.19 per 100,000), Hispanic or Latino people (0.15 per 100,000), and Asian or Pacific Islanders (0.14 per 100,000).
In terms of urbanization, the highest lupus nephritis ASMR was recorded in large central metropolitan areas (>1 million residents), with significantly lower rates reported in large fringe (>1 million), medium (250,000–1 million), and small (50,000–250,000) metropolitan areas, and nonmetropolitan areas (<50,000).
Moreover, Singh and team found that race or ethnicity had a differential association with lupus nephritis mortality risk in the different urbanization locations.
For example, in large central metropolitan areas, Black, Hispanic or Latino, and Asian or Pacific Islander people all had a significantly higher risk for lupus nephritis mortality than White people, with those in the Hispanic group at greatest risk (odds ratio [OR] approximately 15.0).
In all other areas, Black people had the highest odds for lupus nephritis mortality relative to White people, and in nonmetropolitan areas, the risk increase among the Hispanic or Latino and Asian or Pacific Islander groups was no longer significant relative to White people.
“In conclusion, it makes a difference where we live because it can impact your health beyond individual race [or] ethnic factors,” said Singh.
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