Trajectory of Damage Accrual in Systemic Lupus Erythematosus Based on Ethnicity and Socioeconomic Factors

Abstract

Objective The Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) is associated with increased healthcare costs and mortality. We compared the trajectory of total and individual damage items of the SDI in African American vs White ethnicities in a large prospective systemic lupus erythematosus (SLE) cohort. We also estimated the association between ethnicity and individual damage items after adjusting for several socioeconomic factors. Methods Poisson regression was used to calculate the rate of damage per year for each organ. Cox regression modeling was used to determine the association between time to the individual damage item and ethnicity. Results We included 2436 patients: 42.9% African American, 57.1% White, and 92% female. There was a linear relationship between time since diagnosis and mean SDI score, with no plateau. Compared to White patients, African American patients had a faster total, renal, pulmonary, and skin damage accrual rate even after adjustment for differences in socioeconomic variables. Conclusion The linear increase in damage in both ethnicities over time is of particular concern. African American patients accrued more damage at a faster rate compared to White patients. For a few organs, higher rates of damage in African American patients was partially explained by socioeconomic differences, whereas for most organs, the difference persisted after adjustment for these factors.