Annual change in the extracellular fluid/intracellular fluid ratio and mortality in patients undergoing maintenance hemodialysis

We aimed to investigate whether annual change in the extracellular fluid to intracellular fluid (ΔECF/ICF) ratio can accurately predict mortality in hemodialysis patients. Totally, 247 hemodialysis patients were divided into two groups according to the median baseline ECF/ICF ratio of 0.563 and ΔECF/ICF ≥ 0% or < 0% during the first year, respectively. Thereafter, they were divided into four groups according to each cutoff point and were followed up for mortality assessment. The ECF/ICF ratio increased from 0.566 ± 0.177 to 0.595 ± 0.202 in the first year (P = 0.0016). During the 3.4-year median follow-up, 93 patients died (42 cardiovascular-specific causes). The baseline ECF/ICF ≥ 0.563 and ΔECF/ICF ≥ 0% were independently associated with all-cause mortality (adjusted hazard ratio [aHR] 4.55, 95% confidence interval [CI] 2.60–7.98 and aHR 8.11, 95% CI 3.47–18.96, respectively). The aHR for ECF/ICF ≥ 0.563 and ΔECF/ICF ≥ 0% vs. ECF/ICF < 0.563 and ΔECF/ICF < 0% was 73.49 (95% CI 9.45–571.69). For model discrimination, adding the ΔECF/ICF (0.859) alone and both the baseline ECF/ICF and ΔECF/ICF (0.903) to the established risk model (0.746) significantly improved the C-index. Similar results were obtained for cardiovascular mortality. In conclusion, the ΔECF/ICF ratio could not only predict all-cause and cardiovascular mortality but also improve predictability of mortality in hemodialysis patients.