Serum albumin level adjusted with C-reactive protein predicts hemodialysis patient survival

Abstract

BackgroundMalnutrition-related conditions such as protein energy wasting are affecting poor outcome of the dialysis population. The serum albumin level is often used as a marker of wasting and malnutrition. However, the serum albumin level can be affected by the presence of inflammation as well as by nutritional status. We investigated associations between serum albumin values adjusted with C-reactive protein (CRP) and mortality in hemodialysis (HD) patients.MethodsA total of 397 HD patients were included in this study. The patient characteristics and laboratory data, including serum albumin and CRP levels, were obtained in July 2012. Survival as of the end of August 2014 (maximum follow-up period 25 months) was investigated. First, the regression line was obtained from the entire population between serum albumin and CRP levels. Next, the CRP-adjusted albumin levels were determined as a dichotomized variable with the patients having higher albumin values above the regression line. We investigated associations between three albumin indices (the actual values, the dichotomized index by median, and CRP-adjusted values) and mortality by using Cox proportional hazard models.ResultsThe average age of the 397 HD patients was 70.6 years old; 258 were male, and 44.6% were diabetic. Median dialysis vintage was 3.6 years. There were 73 deaths during the observation period. A univariate Cox analysis demonstrated that all three indices were associated with survival, and the hazard ratio (HR) was 0.40 (95% confidence interval (CI) 0.25–0.68) for increase in albumin level, 0.41 (95% CI 0.25–0.68) for higher dichotomized albumin level by median, and 0.46 (95% CI 0.28–0.74) for higher CRP-adjusted albumin level, but only higher CRP-adjusted albumin level was associated with better survival (HR 0.51, 95% CI 0.30–0.85). The degree to which the deviation of albumin was attributable to that of CRP was 12.6%. The analyses on cause-specific mortality revealed that lower albumin levels were associated significantly with infection-related mortality but were not significantly associated with death due to congestive heart failure.ConclusionsCRP-adjusted albumin was shown to be a better predictor of mortality among the HD patients. When assessing serum albumin values, inflammatory status should be taken into account. Malnutrition or wasting was shown to be associated with a poor outcome independent of inflammation.