Abstract
Objective The Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR DI) is associated with increased healthcare cost and mortality. We compared the trajectory of total and individual damage items of the SLICC/ACR DI in African-American vs Caucasian ethnicities in a large prospective 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 2,436 patients: 43% African-American, 57% Caucasian, and 92% female. There was a linear relationship between time since diagnosis and mean SLICC/ACR DI score, with no plateau. Compared to Caucasians, African-Americans 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-Americans accrued more and faster damage compared to Caucasians. For a few organs, higher rates of damage in African-Americans was partially explained by socioeconomic differences, whereas for most organs, the difference persisted after adjustment for these factors.