Determining Predictive Power of Base Excess in Comparison with SOFA Score for Predicting Mortality in ICU Patients.

Abstract

Background: Acid-base disturbances are frequently found in intensive care unit (ICU) patients. Base excess (BE) is commonly used to quantify the degree of metabolic impairment. We aimed to compare the predictive value of BE and Sequential Organ Failure Assessment (SOFA) score for mortality in ICU patients.

Methods: This prospective and observational investigation was performed on 87 ICU patients who underwent mechanical ventilation. SOFA score and acid-base variables at 6 hours of ICU admission were analyzed and compared between survivors and non-survivors. Receiver-operating characteristic (ROC) curve was applied to analyze the predictive value of BE and SOFA for mortality.

Results: Mean age of patients was 63.91±5.03 years, and 60 (69%) were male. The non-survived patients had significantly higher SOFA (P = 0.001) and APACHE II scores (P = 0.001). The non-survived patients had a lower bicarbonate (P = 0.002), PO₂ (P = 0.001), pH (P = 0.0021), and a higher PCO₂ (P = 0.001) compared with survivors, and most patients who died (80%) had a low BE value (< -2) (P = 0.002). The estimated AUC of SOFA and BE was 0.83 (95% CI, 0.73 - 0.92) and 0.71 (95% CI, 0.57 - 0.85), respectively.

Conclusion: BE is, to some extent capable of predicting mortality in ICU patients. However, the SOFA score is a more accurate and reliable parameter in comparison to BE for prediction.