Revisiting mortality predictability of serum albumin in the dialysis population: time dependency, longitudinal changes and population-attributable fraction

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Abstract
Background. Hypoalbuminaemia is a marker of malnutrition–inflammation complex syndrome (MICS) and a strong predictor of cardiovascular (CV) death in maintenance haemodialysis (MHD) patients. However, serum albumin may change over time. Hence, its time-varying associations with outcome may be different. Methods. Associations between 3-month averaged serum albumin levels, measured in a single laboratory using bromocresol green, and CV mortality were studied longitudinally in a 2-year cohort of 58 058 MHD patients. Mortality predictability of fixed baseline and trimonthly-varying serum albumin concentrations were compared. Results. Hazard ratios (HRs) of CV death strictly increased across decrements of baseline serum albumin, whereas the HR for time-varying serum albumin decrements below 3.8 g/dl did not differ. A drop in serum albumin in the first 6 months was associated with increasing all-cause and CV death risks in the subsequent 18 months, while a rise in serum albumin was a predictor of better survival independent of baseline serum albumin. The multivariate adjusted population-attributable fraction of death due to baseline serum albumin 3.8 g/dl might reduce the number of MHD deaths in the USA by ∼10 000 annually. Nutritional interventions examining benefits of increasing serum albumin in MHD patients are urgently needed.