Race/ethnicity, age, and risk of hospital admission and length of stay during the first year of maintenance hemodialysis

Abstract

Background and objectives: Although patients undergoing maintenance hemodialysis have exceptionally high hospitalization rates, the risk factors for hospitalizations are unclear. This study sought to examine hospitalization rates among hemodialysis patients in the United States according to both race/ethnicity and age.

Design, setting, participants, & measurements: US Renal Data System data on 563,281 patients beginning maintenance hemodialysis between 1995 and 2009 were analyzed. Rates of hospital admission and number of hospital days for all-cause and cause-specific hospitalizations during the first year of dialysis were compared among blacks, whites, and Hispanics in the entire cohort and subgroups stratified by age.

Results: After multiple adjustments, compared with whites, Hispanics overall had lower rates of both all-cause hospital days (adjusted rate ratio [aRR], 0.91; 95% confidence interval [95% CI], 0.90 to 0.93; P<0.001) and hospital admissions (aRR, 0.89; 95% CI, 0.88 to 0.90; P<0.001), whereas blacks had a lower rate of all-cause admissions (aRR, 0.95; 95% CI, 0.94 to 0.96; P<0.001). The racial/ethnic differences, however, varied by age. Hispanics exhibited the lowest rates of hospital days and admissions for all age groups≤70 years, but those >80 years had higher rates than their white counterparts. The adjusted black-to-white rate ratios exhibited a U-shaped pattern with age, with higher rates for blacks in the younger and older age groups. Hospitalization rates for dialysis-related infections were markedly higher in blacks and Hispanics than whites, which were consistent in all age groups for blacks (aRRs for hospital days ranged from 1.09 to 1.36) and all ages>60 years for Hispanics (aRRs ranged from 1.20 to 1.38).

Conclusions: There are significant racial/ethnic differences in hospitalization rates within first year of dialysis, which are not consistent across the age groups and also differ by causes of hospitalization. Overall, blacks and Hispanics had lower rates of all-cause hospital admissions than whites. However, younger and older blacks and older Hispanics were at greatest risk.

Keywords: Racial and ethnic differences; USRDS; cardiovascular diseases; dialysis-related infection; hospital days.

Figure 1.

Adjusted rate ratios of hospital days and admissions for blacks and Hispanics compared with whites by age group. (A) All causes. (B) Cardiovascular diseases. (C) All-cause infection. (D) Dialysis-related infection. The error bars represent 95% confidence intervals (95% CIs). All P values for the interaction between race/ethnicity and age were <0.001, except for P=0.05 for the hospital days due to dialysis-related infection.