A composite score of protein-energy nutritional status predicts mortality in haemodialysis patients no better than its individual components

Abstract

Protein-energy wasting is tightly associated with mortality in haemodialysis patients. An expert panel of the International Society of Renal Nutrition and Metabolism (ISRNM) has published a consensus on the parameters that define protein-energy nutritional status and posed the question, 'which scoring system most effectively predicts outcome?' The aim of our study was therefore to develop a composite score of protein-energy nutritional status (cPENS) and to assess its prediction of all-cause mortality. We used the data of 560 haemodialysis patients participating in the CONvective TRAnsport STudy (CONTRAST). All participants were followed for occurrence of death. Internationally recommended nutritional targets were used as components of the cPENS, including the subjective global assessment (target score ≥ 6), albumin (≥ 4.0g/dL), normalized protein nitrogen appearance (≥ 0.8g/kg/day), cholesterol (≥ 100mg/dL), creatinine (≥ 10mg/dL) and BMI (> 23kg/m(2)). A Cox regression model was used to analyse the relation between different cPENS variants and mortality. The median follow-up time was 1.4years (max 4.2). One hundred and five patients (19%) died. A cPENS variant based on albumin, BMI, creatinine and the nPNA yielded the strongest relation with mortality (hazard ratio 0.63, 95% confidence interval 0.54-0.74, P < 0.001), after adjustments for confounders. Some of the individual parameters of the cPENS, notably albumin and creatinine, were related to mortality with similar strength and magnitude. In conclusion, albumin reflects mortality risk similarly to multiple nutritional parameters combined. This questions the clinical value of the proposed diagnostic criteria for protein-energy wasting.