Hypoalbuminemia and acute kidney injury: a meta-analysis of observational clinical studies

PURPOSE: To test the hypothesis that hypoalbuminemia is independently associated with increased risk of acute kidney injury (AKI). METHODS: A meta-analysis was performed of observational clinical studies evaluating the relationship between serum albumin level and the occurrence of AKI by multivariate methods. Additionally, the impact was assessed of lower serum albumin on mortality in patients who developed AKI. Eligible studies were sought by multiple methods, and adjusted odds ratios (OR) were quantitatively combined using a random effects model. RESULTS: Seventeen clinical studies with 3,917 total patients were included: 11 studies (6 in surgical or intensive care unit patients and 5 in other hospital settings) evaluating the influence of serum albumin on AKI incidence and 6 studies describing the relationship between serum albumin and mortality among patients who had developed AKI. Lower serum albumin was an independent predictor both of AKI and of death after AKI development. With each 10 g L(−1) serum albumin decrement, the odds of AKI increased by 134%. The pooled OR for AKI was 2.34 with a 95% confidence interval (CI) of 1.74–3.14. Among patients who had developed AKI, the odds of death rose 147% (pooled OR 2.47, 95% CI 1.51–4.05) with each 10 g L(−1) serum albumin decrement. CONCLUSIONS: This meta-analysis provides evidence that hypoalbuminemia is a significant independent predictor both of AKI and of death following AKI development. Serum albumin determinations may be of utility in identifying patients at increased risk for AKI or for death after AKI. Controlled studies are warranted to assess interventions aimed at correcting hypoalbuminemia.