Laboratory abnormalities at the onset of treatment of end-stage renal disease: are there racial or socioeconomic disparities in care?

Abstract

Background: Laboratory abnormalities at the start of treatment of end-stage renal disease (ESRD) have been reported as worse in racial/ethnic minorities than in white patients, suggesting racial disparities in care. It is not known whether these differences are attributable to racial/ethnic differences in socioeconomic status (SES).

Methods: We tested associations between race/ethnicity, SES, and type of medical insurance and serum creatinine level, estimated glomerular filtration rate, serum albumin level, and hematocrit at the start of treatment of ESRD and use of epoietin before ESRD treatment in a large national population-based sample. Data on 515 561 patients beginning ESRD treatment between January 1, 1996, and June 30, 2004, were obtained for this cross-sectional survey from the United States Renal Data System.

Results: Race/ethnicity had a much stronger association than SES with each laboratory measure. Adjusted mean serum creatinine levels were lowest in white patients (7.5 mg/dL [663.0 micromol/L]; 95% confidence interval [CI], 7.45-7.49) and highest in black patients (8.9 mg/dL [786.7 micromol/L]; 95% CI, 8.92-8.97) (P<.001 across racial/ethnic groups). Adjusted mean hematocrit for white patients (29.5%; 95% CI, 29.4%-29.6%) was significantly higher and for black patients (28.3%; 95% CI, 28.2%-28.4%) significantly lower than that of all other racial/ethnic groups (P<.001 across racial/ethnic groups). Less marked differences were present for estimated glomerular filtration rate and serum albumin level. In contrast, predialysis use of epoietin was associated with race/ethnicity (black vs white: odds ratio, 0.80; 95% CI, 0.78-0.81; Hispanic vs white: odds ratio, 0.87; 95% CI, 0.85-0.89) and showed a graded decrease with decreasing SES (odds ratio for the lowest vs highest socioeconomic quartile 0.68; 95% CI, 0.67-0.70). Patients without medical insurance had more abnormal laboratory values than those with insurance, but these associations were weaker than those of race/ethnicity.

Conclusions: Minorities, particularly black patients, had more severe laboratory abnormalities at the start of ESRD treatment than white patients. These differences were not readily attributable to SES differences. Absence of medical insurance, SES, and race/ethnicity were associated with the likelihood of predialysis use of epoietin.