Racial Disparities and Achievement of the Low Lupus Disease Activity State: A CARRA Registry Study

Abstract

Objective: Differential disease control may contribute to racial disparities in outcomes of childhood-onset systemic lupus erythematosus (cSLE). We evaluated associations of race and individual- or neighborhood-level social determinants of health (SDoH) with achievement of low lupus disease activity state (LLDAS), a clinically relevant treatment target.

Methods: In this cSLE cohort study using the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry, the primary exposure was self-reported race and ethnicity, and collected SDoH included insurance status and area deprivation index (ADI). Outcomes included LLDAS, disease activity, and time-averaged prednisone exposure. Associations among race and ethnicity, SDoH, and disease activity were estimated with multivariable regression models, adjusting for disease-related and demographic factors.

Results: Among 540 children with cSLE, 27% identified as Black, 25% identified as White, 23% identified as Latino/a, 11% identified as Asian, 9% identified as more than one race, and 5% identified as other. More Black children (41%) lived in neighborhoods of highest ADI compared to White children (16%). Black race was associated with lower LLDAS achievement (adjusted odds ratio 0.56, 95% confidence interval [CI] 0.38-0.82) and higher disease activity (adjusted β 0.94, 95% CI 0.11-1.78). The highest ADI was not associated with lower LLDAS achievement on adjustment for renal disease and insurance. However, renal disease was found to be a significant mediator (P = 0.04) of the association between ADI and prednisone exposure.

Conclusions: Children with cSLE who identified as Black are less likely to achieve LLDAS and have a higher disease activity. Living in areas of higher ADI may relate to renal disease and subsequent prednisone exposure. Strategies to address root causes will be important to design interventions mitigating cSLE racial disparities.

Figure 1

Causal mediation analysis for the total effect (3.24, 95% CI 0.62–6.25, P = 0.02) of ADI >75th percentile versus <26th percentile on time‐adjusted mean prednisone dosing separated into its direct effect versus its indirect effect mediated by renal involvement, adjusted for race and ethnicity. The Total Effect is the sum of indirect effect and direct effect of the exposure on the outcome. ADI, area deprivation index; CI, confidence interval.