Analysis of resource use and cost-generating factors in a German medical intensive care unit employing the Therapeutic Intervention Scoring System (TISS-28)

Objective: Evaluation of resource use and costs of a medical intensive care unit (ICU) utilising the simplified Therapeutic Intervention Scoring System (TISS-218). Design: Prospective observational study. Setting: Medical ICU of a tertiary care centre. Patients: Consecutive patients with an ICU length of stay (LOS) more than 24 h. Interventions: Over a 3 month period SAPS II, TISS-28 and SOFA were determined daily. Patients were retrospectively classified as receiving active (AT) or non-active (NAT) treatment according to TISS-28 variables, with AT representing a therapeutic intervention that could not be performed outside the ICU. Individual expenditure for all patients was calculated using, a modified 'top-down' method. Measurements and results: Out of 303 consecutive patients, 241 (79.5%), including all non-survivors, were categorised AT. The hospital mortality was 14.5%. TISS-28 and ICU LOS were higher in patients receiving AT (p<0.001). Patient-specific costs accounted for 36 EUR per TISS-point and daily treatment costs 1336 EUR for all patients. Daily costs of care were 68 EUR higher for AT, compared to NAT, patients (p<0.001). There was no association between ICU costs and measures of severity of illness (SAPS II, SOFA). Conclusions: TISS-28 is a fast, reliable and readily applicable tool to identify patients receiving AT. Although total and daily costs of care were significantly higher in patients receiving AT, the difference of the daily costs was, albeit statistically significant, economically negligible. The main difference in ICU costs was attributable to ICU LOS. Therefore cost-saving strategies must aim at reducing ICU LOS, without compromising quality of care.