Association between a self-rated health question and mortality in young and old dialysis patients: A cohort study

Background: 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. Study Design: Prospective cohort study. Setting & Participants: 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. Predictor: SRH score completed at 3 months after the start of dialysis therapy (baseline). Outcomes & Measurements: 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. Results: 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 [HRadj], 3.56; 95% confidence interval [CI], 1.71 to 7.42; HRadj, 2.09; 95% CI, 1.06 to 4.12; HRadj, 1.87; 95% CI, 0.95 to 3.70, respectively) independent of a range of risk factors. No age interaction with SRH was found. Limitations: Although the SRH-mortality association remained strong despite extensive adjustments, unknown residual confounding could still exist. Conclusion: 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.