Hypoalbuminemia: a risk factor for acute kidney injury development and progression to chronic kidney disease in critically ill patients.

PURPOSE: The increased likelihood of poor outcomes in critically ill patients with hypoalbuminemia is well recognized. However, hypoalbuminemia remains poorly defined as an independent predictor of acute kidney injury (AKI) and stage 4 chronic kidney diseases (CKD4 ). The aim of this study was to assess the role of hypoalbuminemia as an independent risk factor for AKI and CKD4 in critically ill patients.

DESIGN: A retrospective cohort study.

SETTING: General intensive care unit (ICU) at Anhui Provincial Hospital, PR China.

INTERVENTION: None.

MEASUREMENTS AND MAIN RESULTS: We screened patients admitted to the ICU at Anhui Provincial Hospital between January 1, 2008, and October 31, 2011, and included those aged >18 years with available records of serum albumin (SA), baseline serum creatinine, and outcome data. The exclusion criteria were: (1) patients with known AKI and CKD stage 4, 5 before ICU admission; (2) patients lost to follow-up; and (3) patients without research authorization. A total of 588 patients with available data were enrolled in the study, and 62 patients with preexisting CKD stage 4 and CKD stage 5 and 115 with preexisting AKI were excluded. Thirty patients were lost to follow-up. Ultimately, 381 patients were analyzed, 233 (61.2%) of whom developed AKI. Patients with low SA were significantly more likely than those with normal SA (p = 0.0003) to develop AKI, and to progress from AKI to CKD4 (p = 0.0229). More patients in the AKI group than in the non-AKI group had risk factors such as hypotension, mechanical ventilation (MV), proteinuria, sepsis, nephrotoxin exposure, and high-risk surgery (p < 0.01). The difference in duration of MV, ICU days, ICU mortality, hospital days, and hospital mortality between the AKI and non-AKI groups was also significant (p < 0.01). Logistic regression showed that hypoalbuminemia was significantly associated with AKI and CKD4 [odds ratio (OR) 1.810, 95% confidence interval (CI) 1.102-2.992, and OR 2.494, 95% CI 1.231-5.295, respectively]. After 4 years of follow-up, Kaplan-Meier analysis showed that survival in hypoalbuminemia patients was significantly shorter than in patients with normal SA (p = 0.0393). In the Cox proportional hazard model, hypoalbuminemia was an independent predictor of long-term mortality (hazard ratio 1.5, 95% CI 1.042-2.183, p = 0.0291).

CONCLUSION: Hypoalbuminemia in critically ill patients is independently associated with an increased risk of development of AKI and AKI progressing to CKD4 .