Impact of prealbumin levels on mortality in patients with acute kidney injury: an observational cohort study.

OBJECTIVE: We evaluated the prognostic value of prealbumin (transthyretin) levels in patients with acute kidney injury (AKI).

STUDY DESIGN: This was a longitudinal, single-center, observational cohort study.

SETTING: The setting was a university-affiliated hospital.

PARTICIPANTS: One hundred and sixty-one consecutive patients with AKI matched at least one of the Risk, Injury, Failure, Loss, End Stage (RIFLE) criteria for increased serum creatinine, and had requested a nephrology consultation between April 2000 and March 2006.

METHODS: We conducted a computer-assisted review of all cases of AKI seen by a nephrologist between April 2000 and March 2006. We used Cox proportional hazards models to estimate the risk of in-hospital mortality associated with serum prealbumin level at the beginning of the nephrology consultation.

RESULTS: Clinicopathologic variables were compared between patients with a serum prealbumin level <11 mg/dL (the exposed group; cutoff point, median) and patients with a serum prealbumin level > or =11 mg/dL (the control group). In-hospital mortality rates associated with prealbumin levels were 45.0% for <11 mg/dL, and 19.8% for > or =11 mg/dL (P = .001). After adjusted analysis, the presence of a serum prealbumin level <11 mg/dL was significantly associated with increased in-hospital mortality (hazard ratio, 2.10; 95% confidence interval, 1.08 to 4.08), compared with patients with the same Liano scoring, the same RIFLE classes, and the same treatment for AKI, but with a serum prealbumin level > or =11 mg/dL. In addition, each increment of 5 mg/dL of serum prealbumin was associated with an adjusted 29% decrease of in-hospital mortality (hazard ratio, 0.71; 95% confidence interval, 0.52 to 0.96).

CONCLUSIONS: Serum prealbumin levels <11 mg/dL were strongly associated with a higher risk of death, independent of AKI severity, comorbid illnesses, serum C-reactive protein levels, and other possible confounders. The measurement of serum prealbumin levels may be an inexpensive and useful tool in the evaluation of the risk profiles of AKI patients.