Risk stratification in emergency surgical patients: is the APACHE II score a reliable marker of physiological impairment?

HYPOTHESES: The APACHE II (Acute Physiology and Chronic Health Evaluation II) score used as an intensive care unit (ICU) admission score in emergency surgical patients is not independent of the effects of treatment and might lead to considerable bias in the comparability of defined groups of patients and in the evaluation of treatment policies. Postoperative monitoring with the APACHE II score is clinically irrelevant.
DESIGN: Inception cohort study.
SETTING: Secondary referral center. PATIENTS: Eighty-five consecutive emergency surgical patients admitted to the surgical ICU in 1999. The APACHE II score was calculated before surgery; after admission to the ICU; and on postoperative days 3, 7, and 10. MAIN OUTCOME MEASURES: APACHE II scores and predicted and observed mortality rates.
RESULTS: The mean +/- SD APACHE II score of 24.2 +/- 8.3 at admission to the ICU was approximately 36% greater than the initial APACHE II score of 17.8 +/- 7.7, a difference that was highly statistically significant (P<.001). The overall mortality of 32% favorably corresponds with the predicted mortality of 34% according to the initial APACHE II score. However, the predicted mortality of 50% according to the APACHE II score at admission to the ICU was significantly different from the observed mortality rate (P =.02). In 40 long-term patients (>/=10 days in the ICU), the difference between the APACHE II scores of survivors and patients who died was statistically significant on day 10 (P =.04).
CONCLUSIONS: For risk stratification in emergency surgical patients, it is essential to measure the APACHE II score before surgical treatment. Longitudinal APACHE II scoring reveals continuous improvement of the score in surviving patients but has no therapeutic relevance in the individual patient.