Quality-of-life and mortality in hemodialysis patients: roles of race and nutritional status

Abstract

Background and objectives: Maintenance hemodialysis (MHD) patients often have protein-energy wasting, poor health-related quality of life (QoL), and high premature death rates, whereas African-American MHD patients have greater survival than non-African-American patients. We hypothesized that poor QoL scores and their nutritional correlates have a bearing on racial survival disparities of MHD patients.

Design, setting, participants, & measurements: We examined associations between baseline self-administered SF36 questionnaire-derived QoL scores with nutritional markers by multivariate linear regression and with survival by Cox models and cubic splines in the 6-year cohort of 705 MHD patients, including 223 African Americans.

Results: Worse SF36 mental and physical health scores were associated with lower serum albumin and creatinine levels but higher total body fat percentage. Spline analyses confirmed mortality predictability of worse QoL, with an almost strictly linear association for mental health score in African Americans, although the race-QoL interaction was not statistically significant. In fully adjusted analyses, the mental health score showed a more robust and linear association with mortality than the physical health score in all MHD patients and both races: death hazard ratios for (95% confidence interval) each 10 unit lower mental health score were 1.12 (1.05-1.19) and 1.10 (1.03-1.18) for all and African American patients, respectively.

Conclusions: MHD patients with higher percentage body fat or lower serum albumin or creatinine concentration perceive a poorer QoL. Poor mental health in all and poor physical health in non-African American patients correlate with mortality. Improving QoL by interventions that can improve the nutritional status without increasing body fat warrants clinical trials.

Copyright © 2011 by the American Society of Nephrology

Figures

Figure 1.

Serum albumin level across four quartiles of the two dimensions and eight scales of SF36 (error bars indicate SD). SF36 consists of two main dimensions, mental health and physical health, and each dimension consists of five subscales. 1) Mental Health consists of role mental, mental health, social function, vitality, and general health). 2) Physical health consists of physical function, role physical, body pain, vitality, and general health. Detail in appendix.

Figure 2.

Serum creatinine level across the four quartiles of the two dimensions and eight scales of SF36 (error bars indicate SD). SF36 consists of two main dimensions, mental health and physical health, and each dimension consists of five subscales. 1) Mental Health consists of role mental, mental health, social function, vitality, and general health). 2) Physical health consists of physical function, role physical, body pain, vitality, and general health. Detail in appendix.

Figure 3.

Total body fat percentage (assessed by NIR) across the four quartiles of the two dimensions and eight scales of SF36 (error bars indicate SD). SF36 consists of two main dimensions, mental health and physical health, and each dimension consists of five subscales. 1) Mental Health consists of role mental, mental health, social function, vitality, and general health). 2) Physical health consists of physical function, role physical, body pain, vitality, and general health. Detail in appendix.

Figure 4.

Cubic spline survival analyses exhibiting the association between SF36 scores and mortality in 705 MHD patients over 6 years. (Left) Mental health score (P < 0.001). (Right) Physical health score (P < 0.001).

Figure 5.

Cubic spline survival analyses exhibiting the association between SF36 mental health score and mortality over 6 years. (Left) 482 non-African–American MHD patients (P < 0.001). (Right) 223 African-American MHD patients (P < 0.001).

Figure 6.

Cubic spline survival analyses exhibiting the association between SF36 physical health score and mortality over 6 years. (Left) 482 non-African–American MHD patients (P < 0.001). (Right) 223 African-American MHD patients (P > 0.20).