Survival Disparity of African American Versus Non-African American Patients With ESRD Due to SLE

Abstract

Background: A recent study showed an increased risk of death in African Americans compared with whites with end-stage renal disease (ESRD) due to lupus nephritis (LN). We assessed the impact of age stratification, socioeconomic factors, and kidney transplantation on the disparity in patient survival among African American versus non-African American patients with LN-caused ESRD, compared with other causes.

Study design: Retrospective cohort study.

Setting & participants: Using the US Renal Data System database, we identified 12,352 patients with LN-caused ESRD among 1,132,202 patients who initiated maintenance dialysis therapy from January 1, 1995, through December 31, 2006, and were followed up until December 31, 2010.

Predictors: Baseline demographics and comorbid conditions, Hispanic ethnicity, socioeconomic factors (employment status, Medicare/Medicaid insurance, and area-level median household income based on zip code as obtained from the 2000 US census), and kidney transplantation as a time-dependent variable.

Outcome: All-cause mortality.

Measurements: Multivariable Cox and competing-risk regressions.

Results: Mean duration of follow-up in the LN-caused ESRD and other-cause ESRD cohorts were 6.24±4.20 (SD) and 4.06±3.61 years, respectively. 6,106 patients with LN-caused ESRD (49.43%) and 853,762 patients with other-cause ESRD (76.24%) died during the study period (P<0.001). Patients with LN-caused ESRD were significantly younger (mean age, 39.92 years) and more likely women (81.65%) and African American (48.13%) than those with other-cause ESRD. In the fully adjusted multivariable Cox regression model, African American (vs non-African American) patients with LN-caused ESRD had significantly increased risk of death at age 18 to 30 years (adjusted HR, 1.43; 95% CI, 1.24-1.65) and at age 31 to 40 years (adjusted HR, 1.17; 95% CI, 1.02-1.34). Among patients with other-cause ESRD, African Americans were at significantly increased risk at age 18 to 30 years (adjusted HR, 1.17; 95% CI, 1.11-1.22).

Limitations: We used zip code-based median household income as a surrogate for patient income. Residual socioeconomic confounders may exist.

Conclusions: African Americans are at significantly increased risk of death compared with non-African Americans with LN-caused ESRD at age 18 to 40 years, a racial disparity risk that is 10 years longer than that in the general ESRD population. Accounting for area-level median household income and transplantation significantly attenuated the disparity in mortality of African American versus non-African American patients with LN-caused ESRD.

Keywords: African American; Racial disparity; US Renal Data System (USRDS); all-cause mortality; competing risk; dialysis; end-stage renal disease (ESRD); kidney transplantation; lupus nephritis; survival disparity; systemic lupus erythematosus (SLE).