Outcome assessment--TISS as a tool to evaluate cost-effectiveness of immunological treatment

Nursing costs more than any other element of intensive care. Nurses are allocated exclusively to the ICU, and their use can therefore be accurately monitored. The amount of nursing work in the ICU is intimately associated with the severity of illness of the patients. Consequently, the density of nursing staff in the ICU can be used as a measure of cost, and the Therapeutic Intervention Scoring System (TISS) is a reliable tool for measuring their workload. TISS is therefore often used to compare the costs of alternative courses of care; it covers direct costs of care, but it should not be used as a proxy for total costs in the ICU. The users of TISS should consider the limitations of the scoring system in some aspects of its development, as well as the general nature of the definitions of the items included. The careful enunciation of the more generally defined items has therefore to be considered when it is used in a research project that compares small samples.