Diminishing dry weight is strongly associated with all-cause mortality among long-term maintenance prevalent dialysis patients

OBJECTIVES: To investigate the relationship between dry weight (DW) change and survival in long-term maintenance prevalent dialysis patients. METHODS: We conducted a prospective data collection study with retrospective analysis of the registered data. Patients were followed up for 5 years (1-year observation of DW changes and subsequent 4-year follow-up). The outcome was all-cause mortality. The predictors were 1-year DW change rates. The hazard ratios (HRs) for all-cause mortality were calculated using multivariable Cox regression analysis, fully adjusted for age, sex, basal kidney disease, dialysis vintage, current smoking, past cardiovascular events, serum albumin, DW at enrollment, serum creatinine, mean predialysis systolic blood pressure, and cardiothoracic ratio or 1-year cardiothoracic ratio change rate. Propensity score (PS) analysis was also conducted using the same covariates of Cox regression analysis. RESULTS: In total, 899 dialysis patients (mean dialysis vintage: 101.2 months) were followed up, and 180 deaths were recorded, of which 90 were of cardiovascular origin. Each 2% decrement of DW showed adjusted HR, and the 95% confidence interval was 1.24 [1.16–1.33]. According to the 1-year DW change rate, participants were divided into five groups (group A, ≥+3%; group B, +1 to +2.9%; group C, -0.9 to +0.9%; group D, -2.9 to -1.0%; and group E, ≤-3%). For survival curves based on grouping, group B had the best and group E had the worst survival rate (p<0.01, log-rank test). Therefore, we set group B as a reference; adjusted risks for death of groups D and E were 2.16 [1.23–3.79] and 2.66 [1.54–4.58], respectively. However, this relation was blunted in patients of heavier DW. The PS-matched cohort showed a poorer prognosis in patients with diminishing DW divided by DW change rate at -0.635% (mean value of DW change rate). CONCLUSION: In the long-term maintenance hemodialysis cohort, 1-year DW decrement, especially ≤-3.0%, was significantly associated with all-cause mortality, and cardiovascular disease-related death was prominent in these patients.