Serum albumin and mortality risk in critically ill patients

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Introduction

It had been shown that serum albumin measured within 48 h of ICU admission is as accurate as the APACHE II score in predicting hospital mortality. If this result could be confirmed, then albumin would be a cheaper and more convenient predictor of mortality than APACHE II.

Aim

To evaluate serum albumin as a predictor of hospital mortality in critically ill patients.

Methods

All consecutive adult ICU admissions over an 18 month period (April 1997 to September 1998) were reviewed. The data were retrieved from a computerised database. Serum albumin concentrations between survivors and nonsurvivors were compared. Accuracy of outcome prediction using albumin was assessed by area under the curve (AUC) of the receiver operator characteristics (ROC) curve.

Results

1003 records were reviewed. There were 647 (64.5%) survivors and 356 (35.5%) nonsurvivors. The survivors had a significantly higher serum albumin both on ICU admission and in the first 72 h after admission (P<0.001) (see Fig. 1). In both groups, the serum albumin fell markedly after ICU admission. The ROC curves for hospital mortality are shown in Fig. 2. The AUC of APACHE II (0.79) is significantly higher than that of admission albumin (0.63) and albumin at 24 h (0.64) (P<0.001). We used regression analysis to combine APACHE II with admission albumin (AUC 0.80) and APACHE II with albumin at 24 h (AUC 0.79) to predict hospital mortality. The addition of albumin did not significantly improve the accuracy of outcome prediction over that of APACHE II alone.

Figures

1(left) and 2 (right)

Conclusion

There is an association between serum albumin concentration and hospital mortality. However, as a single variable, serum albumin is a poor predictor of hospital outcome. Combining APACHE II with admission albumin or albumin at 24 h did not improve the accuracy of outcome prediction over that of APACHE II score alone.