Determining the economic cost of ICU treatment: a prospective "micro-costing" study

To prospectively assess the cost of patients in an adult intensive care unit (ICU) using bottom-up costing methodology and evaluate the usefulness of "severity of illness" scores in estimating ICU cost. A prospective study costing 64 consecutive admissions over a 2-month period in a mixed medical/surgical ICU. The median daily ICU cost (interquartile range, IQR) was a,not sign2,205 (a,not sign1,932-a,not sign3,073), and the median total ICU cost (IQR) was a,not sign10,916 (a,not sign4,294-a,not sign24,091). ICU survivors had a lower median daily ICU cost at a,not sign2,164 per day, compared with a,not sign3,496 per day for ICU non-survivors (P = 0.08). The requirements for continuous haemodiafiltration, blood products and anti-fungal agents were associated with higher daily and overall ICU costs (P = 0.002). Each point increase in SAPS3 was associated with a a,not sign305 (95% CI a,not sign31-a,not sign579) increase in total ICU cost (P = 0.029). However, SAPS3 accounted for a small proportion of the variance in this model (R (2) = 0.08), limiting its usefulness as a stand-alone predictor of cost in clinical practice. A model including haemodiafiltration, blood products and anti-fungal agents explained 54% of the variance in total ICU cost. This bottom-up costing study highlighted the considerable individual variation in costs between ICU patients and identified the major factors contributing to cost. As the requirement for expensive interventions was the main driver for ICU cost, "severity of illness" scores may not be useful as stand-alone predictors of cost in the ICU.