Systems for scoring severity of illness in intensive care.

Severity of illness scoring systems are increasingly being used by many intensive care units to predict mortality and to compare results and different therapies. A study was undertaken to evaluate three of these systems--therapeutic intervention scoring system (TISS), acute physiology and chronic health evaluation (APACHE II), and organ failure--in a 2-year prospective analysis in a multidisciplinary intensive care unit. A total of 728 patients with a wide variety of diseases were entered into the study. The relationship between score and mortality in all patients and in specific groups was investigated. The APACHE II system is likely to be the most useful in comparing different therapies and intensive care units, while the organ failure system was more accurate in predicting outcome. No system was precise enough in its predictive powers to make decisions to deny or terminate treatment.