Association of extracellular water/total body water ratio with protein-energy wasting and mortality in patients on hemodialysis

Abstract

Bioimpedance analysis-assessed extracellular water/total body water (ECW/TBW) ratio may be a marker for mortality and poor nutritional status in hemodialysis patients. In 193 maintenance hemodialysis patients, we retrospectively investigated the relationships among ECW/TBW ratio, mortality, and protein-energy wasting (PEW). Four components—body mass index, normalized protein catabolic rate, normalized serum creatinine level, and serum albumin level—constitute the simple PEW score; this score was calculated based on the positive number of items concerning malnutrition among these four components. A score ≥ 3 indicated PEW. Patients were stratified by an ECW/TBW ratio cut-off value (0.40) and by PEW versus non-PEW status. The simple PEW score, cardiothoracic ratio, and log-transformed C-reactive protein level were independently correlated with the ECW/TBW ratio. Eighty-four patients died during follow-up (median 4.3 years). After adjustments for sex, age, hemodialysis vintage, histories of cardiovascular events and diabetes, and C-reactive protein level, a higher ECW/TBW ratio and PEW were independently related to elevated risks of all-cause death. Adding the ECW/TBW ratio to a baseline risk model including PEW significantly increased C-statistics from 0.788 to 0.835. In conclusion, the ECW/TBW ratio may be an indicator of PEW and may be a predictor of death even accounting for PEW, in hemodialysis patients.