Do income level and race influence survival in patients receiving hemodialysis?

BACKGROUND: Residence in a lower-income area has been associated with higher mortality among patients receiving dialysis. We sought to determine whether these differences persist and whether the effect of income-area on mortality is different for African Americans versus patients of other races.
METHODS: We evaluated relationships between lower- and higher-income versus middle-income area residence and mortality to 5 years after adjusting for differences in baseline clinical, dialysis facility, and socioeconomic characteristics in 186,424 adult patients with end-stage renal disease initiating hemodialysis at stand-alone facilities between 1996 and 1999. We also compared mortality differences between race and income level groups using non-African Americans residing in middle-income areas as the reference group.
RESULTS: Patients with end-stage renal disease who reside in lower-income areas were younger and more frequently African American. After adjustment, there were no mortality differences among income level groups. However, African Americans in all income level groups had lower adjusted mortality compared with the reference group (lower-income hazard ratio [HR]=0.771, 95% confidence interval [CI], 0.736-0.808; middle-income HR=0.755, 95% CI, 0.730-0.781; higher-income HR=0.809, 95% CI, 0.764-0.857), whereas adjusted mortality was similar among non-African-American income level groups (lower-income HR=1.019, 95% CI, 0.976-1.064; higher-income HR=1.003, 95% CI, 0.968-1.039).
CONCLUSION: Adjusted survival for patients receiving hemodialysis in all income areas was similar. However, this result masks the paradoxically higher survival for African American versus patients of other race and demonstrates the need to adjust for differences in demographic, clinical, provider, and socioeconomic status characteristics.