Lupus nephritis and socioeconomic status: Findings from the Southern California lupus registry

Abstract

Objective Lupus nephritis (LN) is a major cause of morbidity and mortality in systemic lupus erythematosus (SLE). Despite multiple studies addressing healthcare disparities, disparate outcomes in LN persist. We investigate herein the association between socioeconomic status (SES) and LN as well as the association between SES, SLE disease activity index (SLEDAI), and treatment response. Methods Patients were selected from the Southern California Lupus Registry (SCOLR), a registry enrolling all-comers with SLE. Analysis was completed on individuals with public vs. private insurance. Insurance and ethnicity were used as surrogate variables for SES, and we tested differences in means. Results After adjusting for age and sex, public insurance was independently associated with the prevalence of LN. Analysis of 35 patients revealed greater proteinuria and mean SLEDAI in patients with public insurance at baseline and 6 months. Baseline, 6-, and 12-month SLEDAI means were significantly lower in Asian/Pacific Islanders (PI) compared to others. While non-Hispanic Whites demonstrated mean SLEDAI improvement over 6 months, Asians/PI, Blacks, and Hispanics demonstrated worsened disease activity on average. Conclusion Low SES, when defined by insurance, is associated with greater adverse outcomes in SLE. This is the first regional study that compares differences in treatment response in LN patients with low SES as well as association of SES with long-term outcomes in SLE and LN in southern California.