POS1169 INCOME, RACE/ETHNICITY, AND URBAN-RURAL RESIDENTIAL REGION AS DETERMINANTS OF MORTALITY IN LUPUS NEPHRITIS
Authors: S. Rajkumar, E. Yen, L. Chen, R. Singh
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Lupus nephritis (LN) is a chronic kidney disease with poor outcomes in minority racial/ethnic communities. <h3>Objectives:</h3> Assess the impact of income, race/ethnicity, and urbanicity on LN mortality. <h3>Methods:</h3> We obtained data from the US Census Bureau on median household incomes in all U.S. counties for 2003, 2008, 2013, and 2018 and averaged them to represent the median household income for the study period (1999-2019). We used the Center for Disease Control and Prevention's WONDER database, which compiles mortality data from death certificates in all 50 states and the District of Columbia. We obtained data on LN deaths by three income groups (&lt;45,000, 45000-59,999, and ≥60,000 US dollars), five race/ethnicity [Hispanic, non-Hispanic (NH) white (white), NH-black (black), NH-Asian/Pacific Islander (Asian/PI), and NH-American Indian/Alaska Native (AI/AN)] and five urbanization categories [large central metro, large fringe metro, medium metro, small metro, and nonmetro (micropolitan + noncore) from 1999 through 2019. We calculated age-standardized mortality rate (ASMR) per 100,000 people for LN deaths. To identify any effect modification, we performed multivariable logistic regression analysis to obtain incidence rate ratios (IRR) without and with interactions in the model. <h3>Results:</h3> Relative to the highest income group, the adjusted IRR was significantly high in the lowest (1.24, 95% CI 1.15-1.33, p&lt;0.001) and middle-income groups (1.15, 95% CI, 1.08-1.22). The adjusted IRR was highest in the NH-black (4.60, 95% CI, 4.38-4.82) followed by NH-other (1.62, 95% CI, 1.48-1.78) and Hispanic (1.41, 95% CI, 1.32-1.50) groups relative to NH-white group. Large fringe metro ('suburbs') and small metro areas had significantly lower adjusted IRR (0.89 and 0.91, p&lt;0.001) relative to large central metros ('inner cities'). There were significant interactions between income and urbanization categories and between race/ethnicity and urbanization, but not between race/ethnicity and income, in modifying LN mortality IRRs. The most significant synergistic interaction was detected between the lowest-income group and nonmetro-area residents (3.24, 95% CI 1.60-6.56, p=0.001), followed by the middle-income group in nonmetro areas (2.47, 95% CI, 1.22-5.03, p=0.01). Synergistic interactions were also detected between the lowest income group and residence in large fringe metro (1.62, p&lt;0.001) and medium metro (1.24, p=0.01), middle income and large fringe metro (1.39, p&lt;0.001), and NH-other and medium metro (1.31, p=0.02). There were significant antagonistic interactions between residents in large fringe metro and Hispanic (0.76, p&lt;0.01), large fringe metro and NH-other (0.77, p=0.05), and non-metro and Hispanic groups (p&lt;0.05). <h3>Conclusion:</h3> Income, race/ethnicity, and urbanicity are independently and interactively associated with LN mortality. Urbanicity modified the race/ethnicity's impact on LN death rate ratios in all communities except in NH-black persons, and income modified the impact of urbanicity on LN death rate ratios. Overall, living in large fringe metro (suburbs) was associated with a protective effect in all race/ethnic groups except in black persons. In contrast, low household incomes were associated with worse LN mortality rates in all urban-rural residences, particularly in nonmetro areas. Studies are needed to verify these findings at the individual level and to understand the underlying disparities in LN mortality by income, race/ethnicity, and neighborhood. These studies would pave the way for precision public health measures to mitigate excess LN mortality in high-risk groups such as individuals with low incomes living in non-metro areas. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>