Background/Purpose: Mortality from SLE has improved over the last two decades, but remains disproportionately high relative to general population mortality. Lupus nephritis (LN) occurs in 50-80% of childhood-onset and over 40% of adult-onset SLE patients. End-stage renal disease (ESRD) due to LN portends a high premature death burden compared to other manifestations of SLE – up to 26-times higher – and double the risk for hospital mortality compared with patients with all-cause ESRD. However, there have been no major population-based studies on mortality trends in LN over time across the U.S. We aimed to analyze mortality trends across the United States (U.S.) over two decades, 1999-2019, and to identify population characteristics associated with LN mortality.

Methods: We utilized the CDC’s WONDER database that compiles mortality data from death certificates in all 50 states and District of Columbia. We obtained death counts attributed to SLE and LN, overall and by race/ethnicity and urbanization. Data on race/ethnicity were obtained for Hispanic, non-Hispanic (NH) White, NH Black, NH American-India/Alaska Native, and NH Asian/Pacific Islander. Urbanization was based off the 2006 urbanization data and is categorized based on population size – large central metropolitan (metro), large fringe metro, medium metro, small metro, micropolitan, and nonmetropolitan. Using these data, we calculated age-standardized mortality rate (ASMR) per 100,000 persons for LN deaths for each year from 1999 to 2019. We used joinpoint regression to fit piecewise-linear trends to yearly LN-ASMR, and for SLE-ASMR for comparison.

Results: From 1999 to 2019, there were 8,899 deaths attributed to LN and 25,973 deaths due to SLE. Overall, LN-ASMR decreased by 26.1% in 21 years. Joinpoint trend analysis showed that LN-ASMR decreased from 1999 to 2009, plateaued between 2009 and 2012, decreased again from 2012 to 2015, but significantly increased from 2015 to 2019. Such decrease-and-increase trend was not seen in all SLE-ASMR that continuously decreased from 1999 through 2019. Black persons were profoundly overrepresented in LN deaths (38%), while they account for only 12.8% of US population. On the other hand, white persons that represent 65.4% of US population accounted for 41.5% of all LN deaths. LN-ASMR in black persons was 6-fold higher than in white persons and >2-fold higher than in all other race/ethnic groups. LN-ASMR was also significantly higher in Hispanics, American-Indian/Alaska Natives, and Asian/Pacific Islanders than in white persons. Whereas 29.6% of US population lived in large central metro area, they accounted for 35.1% of LN deaths. LN-ASMR was highest in large central metro (p< 0.05 relative to all other areas), followed by medium metro that had higher LN-ASMR than in large fringe metro, small metro, micropolitan and nonmetro areas.

Conclusion: LN mortality rate has decreased since 1999, however, it showed an increasing trend from 2015 to 2019. LN mortality exhibited profound disparities by race/ethnicity and place of residence, with higher mortality in non-white persons and in those living in large central and medium metro. Studies are urgently needed to understand reasons underlying these disparities and the recent worsening trend.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/lupus-nephritis-mortality-in-the-united-states-1999-2019-profound-disparities-by-race-ethnicity-and-place-of-residence-and-a-recent-worsening-trend/