Severity of illness, critical events, organ failure assessment and ICU outcome

Full text

Background

The use of general outcome prediction models in the ICU remains controversial: 1) none of the existing systems is able to precisely predict individual outcome; 2) based on data collected within the first 24 h after admission, their prediction power is insensitive to alternative courses of care (and of ways-of-working) in the ICU.

Objectives

To evaluate the importance of intermediate outcomes of care upon the final outcome of patient care in the ICU; to evaluate whether the consideration of intermediate outcomes of care do increase the predictive power of SAPS II score.

Design

Prospective, multi-center and multinational study.

Setting

47 ICU's from 9 European countries.

Methods

All consecutive admissions were enrolled during a four-month period.

Patient data

admission data; first day SAPS II score; hourly registration of Critical Events (CrEv) defined as the duration (in hours) of out-of-range measurements of four parameters (heart rate, blood pressure, urine output and oxygen saturation); Sequential Organ Failure Score (SOFA) at admission and then every 24 h; ICU outcome.

Measurements

Final outcome: ICU mortality. Intermediate outcomes: SOFA and CrEv, expressed as the percentage of time spent in CrEv (single or combined). SOFA computations included total daily score and Delta-SOFA [1].

Analysis

variables included for explaining final outcome (the dependent variable) on Day 3 through Day 10: Day 1 SAPS II score; intermediate outcome variables (SOFA and CrEv) on Day 1, Day 3 and Day 5.

Results

Data on 1633 patients were analysed: median age of 69 years; median SAPS II score of 35 and ICU mortality rate of 14%. Including the variables indicated in a logistic regression, three models (Table) could be constructed.

Conclusion

Confirming previous studies, the predictive power of first day SAPS II score decreases over time. The inclusion of intermediate outcomes contributes, significantly, to explain ICU mortality. This study strongly suggests the importance of accurate control of processes of care (and the way of working) in the ICU: showing that the incidence and time spent in out-of-range measurements are clearly associated to the final outcome of ICU-patients.

Table