An association between time-varying serum albumin level and the mortality rate in maintenance haemodialysis patients: a five-year clinical cohort study

BACKGROUND Until now, no long-term studies relating serum albumin level to mortality rate in prevalent haemodialysis (HD) patients have been conducted. We aimed to examine the association between serum albumin level and mortality over a 5-year period. METHODS This study included 781 patients who received maintenance HD in a large, hospital-facilitated HD centre. Five-year medical records (2009-2013) were retrospectively reviewed, and the cut-off level for serum albumin level was set at 3.5 g/dL. The analysed albumin levels were expressed as time-averaged levels (first 24-month data) and albumin target reach rate over the first 2-year interval. Univariate and multivariate Cox proportional hazard regression models were used to examine the hazard function of the all-cause and cardiovascular mortality of the study participants in the subsequent 3-year period (2011-2013). RESULTS Compared to those with a 100 % albumin reach rate (3.5 g/dL), the participants with 75- < 100, 50- < 75, and 1- < 50 % albumin reach rates exhibited significantly increased risk for all-cause mortality (HR 1.72, 95 % CI 1.19-2.47; HR 3.14, 95 % CI 1.91-5.16; HR 3.66, 95 % CI 2.18-6.16, respectively). A similar trend for all-cause mortality was demonstrated in participants with time-averaged albumin levels <4 g/dL (HR 1.57, 95 % CI 1.00-2.46 for 3.5-4.0 g/dL; HR 3.66, 95 % CI 2.11-6.32 for <3.5 g/dL). Compared to a 100 % albumin reach rate, the 50- < 75 and 1- < 50 % groups (HR 4.28, 95 % CI 1.82-10.01; HR 3.23, 95 % CI 1.22-8.54 respectively) showed significantly higher cardiovascular mortality rates. Similarly, participants with a time-averaged serum albumin level <3.5 g/dL exhibited a higher risk for cardiovascular mortality (HR 3.24, 95 % CI: 1.23-8.56). CONCLUSIONS This long-term study demonstrated that higher reach rates of serum albumin levels and higher time-averaged serum albumin levels are associated with a lower mortality rate in patients undergoing maintenance HD.