Biostatistical aspects of outcome evaluation using TISS-28

Quantification of therapeutic activities using the Therapeutic Intervention Scoring System (TISS) is an alternative approach to evaluate outcome of pa tients in intensive care. The reason for using cumulative TISS points is to integrate various adverse events (except mortality) according to the amoun t of therapeutic effort that they require. The reduced version of TISS with 28 items (TISS-28) allows a reliable asses sment of therapeutic activities with limited observer variation, provided t hat an exact description of all items is given. Measurements can be validat ed by correlations with established severity of -disease classification sys tems such as APACHE II. Cumulative TISS-28 values correlate well with lengt h of ICU stay (r = 0.98). On average, 27.2 points/day can be expected in an unselected mixed surgical ICU. Those who die can be included in non-parametric analyses of cumulative TISS values by allocation of arbitrary high values. Quantification of therapeut ic interventions is a sensitive measure of outcome in patients who require intensive care but have a low risk of mortality. The usefulness of economic analysis further supports its clinical application.