Association Between a Self-Rated Health Question and Mortality in Young and Old Dialysis Patients: A Cohort Study

Abstract

Self-rated health (SRH) has been shown to predict mortality in large community-based studies; however, large clinical-based studies of this topic are rare. We assessed whether an SRH item predicts mortality in a large sample of incident dialysis patients beyond sociodemographic, disease, and clinical measures and possible age interaction. Prospective cohort study. 1,443 predominantly white patients from 38 dialysis centers in The Netherlands participating in the Netherlands Cooperative Study on the Adequacy of Dialysis-2 between 1997 and 2004. SRH score completed at 3 months after the start of dialysis therapy (baseline). Cox proportional hazards model estimated the association between SRH and all-cause mortality. Interaction of SRH with age (<65 and >/=65 years) was examined in an additive model. Mean age of patients was 59.6 +/- 14.8 years, with 61% men and 69% married/living together. Mean follow-up was 2.7 +/- 1.8 years. Deaths per SRH group in the multivariate analyses sample: excellent/very good (9 of 63 patients; 14.3%), good (148 of 473 patients; 31.3%), fair (194 of 508 patients; 38.2%), and poor (45 of 71 patients; 63.4%). Patients with poor, fair, or good health ratings had a greater mortality risk than those with excellent/very good health ratings (adjusted hazard ratio [HR(adj)], 3.56; 95% confidence interval [CI], 1.71 to 7.42; HR(adj), 2.09; 95% CI, 1.06 to 4.12; HR(adj), 1.87; 95% CI, 0.95 to 3.70, respectively) independent of a range of risk factors. No age interaction with SRH was found. Although the SRH-mortality association remained strong despite extensive adjustments, unknown residual confounding could still exist. SRH is an independent predictor of mortality in incident dialysis patients. Patients with poor SRH in both age strata had a significantly increased risk of mortality even after controlling for demographic and clinical confounders. Patient self-assessment of health can be an invaluable and economical complement to clinical measures in risk assessment.