Serum uric acid as a clinically useful nutritional marker and predictor of outcome in maintenance hemodialysis patients

Objective: The importance of serum uric acid (SUA) for the maintenance of a hemodialysis (MHD) population has not been well established. The aim of this study was to determine if SUA levels are associated with nutritional risk and consequently with adverse clinical outcomes in MHD patients. Methods: This was a 2-y prospective observational study, performed on 261 MHD outpatients (38.7% women) with a mean age of 68.6±13.6y. We measured prospective all-cause and cardiovascular (CV) hospitalization and mortality, nutritional scores (malnutrition-inflammation score [MIS) and geriatric nutritional risk index (GNRI), handgrip strength (HGS), and short-form 36 (SF36) quality-of-life (QoL) scores. Results: SUA positively correlated with laboratory nutritional markers (albumin, creatinine), body composition parameters, HGS (r=0.26; P<0.001) and GNRI (r=0.34; P<0.001). SUA negatively correlated with MIS (r=-0.33; P<0.001) and interleukin-6 (r=-0.13; P=0.04). Patients in the highest SUA tertile had higher total SF-36 scores (P=0.04), higher physical functioning (P=0.003), and role-physical (P=0.006) SF-36 scales. For each 1mg/dL increase in baseline SUA levels, the first hospitalization hazard ratio (HR) was 0.79 (95% confidence interval [CI], 0.68-0.91) and first CV event HR was 0.60 (95% CI, 0.44-0.82); all-cause death HR was 0.55 (95% CI, 0.43-0.72) and CV death HR was 0.55 (95% CI, 0.35-0.80). Associations between SUA and mortality risk continued to be significant after adjustments for various confounders including MIS and interleukin-6. Cubic spline survival models confirmed the linear trends. Conclusions: In MHD patients, SUA is a good nutritional marker and associates with body composition, muscle function, inflammation, and health-related QoL, upcoming hospitalizations, as well as independently predicting all-cause and CV death risk.