[Prognostic scores in intensive care]

Since the development of prognostic score systems in intensive care medicine in the 1980s score models have improved substantially and are now based on much larger databases. They have been validated in many multicenter and international studies all over the world. Prognostic scoring systems may be used for assessment of severity of illness, stratifying patients prior to randomization in clinical trials, evaluation and comparing outcome and survival (hospital mortality), quality assessment, cost-benefit analysis, and in clinical decision making. Validated time points for predicting hospital mortality of ICU patients are at admission and at 24 hours. The relationship of the observed hospital mortality rate to the estimated mortality provides the basis for clinical performance measurement. Since each ICU serves a different patient population, each score system must be calibrated in the individual hospital to ensure that the model is applicable. General scores covering more than one disease are Acute Physiology And Chronic Health Evaluation (APACHE II, APACHE III), Simplified Acute Physiology Score (SAPS) and Mortality Predicting Model (MPM). The Therapeutic Intervention Scoring System (TISS) and in part the Hannover Intensive Score (HIS) evaluate exclusively the amount of medical therapy required. The TISS-Score might serve as a possible measure of resource use for the ICU portion of the hospital stay. Disease (e.g. Trauma Score, Injury of Severity Score) and patient (e.g. PRISM = Pediatric Risk of Mortality) specific scores take into account the influence of disease and patient population in relation to outcome. They are not always of more predictive value than general score models. Score models have been criticized for a number of reasons. Outcome of ICU therapy should incorporate not only survival but should also take into account quality of life, morbidity and disability. Severity scores have no role in clinical decision making for an individual patient (e.g. patient triage for ICU admission, discharge criteria, withdrawal of life support). This is due to the current low sensitivity. Subsequent validation of variables could improve the sensitivity and the value of severity scoring in the future. Nevertheless, illness severity scores will never be indicative of absolute irreversibility of disease or impossibility of survival. Advances in computer technology should assist in achieving many of the future goals of prognostic scoring systems. Most of the physiological data are available from ICU monitors and computerized laboratory systems. By electronically interfacing with the ICU monitor an automated patient data entry is possible and will provide that prognostic scores can be made available to the clinician daily.