Abstract: A system and method are provided for assessing the degree of critical illness of patients in Intensive Care Units (ICUs), and the detection of occurrence of specific clinical outcomes, pursued through the monitoring of a variety of physiological signals, extraction of multiple measures of variability, and integration of the relevant information the measures of variability bring. The integration process leads to the creation of a compound variable, referred to as a composite measure of variability, which can be tuned to various clinical needs, since the process of normalization, feature selection and data integration are customizable to the clinical indication, planned use of the composite variability monitoring. The system and method also enable joining the composite measure of variability with clinical factors, so as to estimate the likelihood of developing specific clinical outcomes.