Objectives: To estimate the actual cost savings that could be achieved through reductions in intensive care unit (ICU) length of stay and duration of mechanical ventilation by determining the short-run marginal variable cost of an ICU and ventilator day.
Research design: Retrospective cohort study in a university-affiliated teaching hospital.
Subjects: All patients receiving mechanical ventilation in the ICU for more than 48 hours (n = 1778) from July 1, 2005 to June 30, 2006.
Measures: The hospital's administrative and cost databases were used to determine total costs, variable costs, and direct-variable costs for each patient on each individual ICU and hospital day.
Results: Direct-variable costs comprised 19.3% of total ICU costs and 18.4% of total hospital costs. Marginal direct-variable costs (the cost of each additional ICU day) were small compared with the average daily total cost ($649 to $839 vs. $1751, in US dollars). In survivors with ICU lengths of stay more than 3 days, the mean direct-variable cost of the last ICU day was $397, while the mean direct-variable cost of the first ward day was $279, for a mean cost difference of $118 (95% CI, $21-$190). Reducing ICU and hospital length of stay by 1 day in all survivors with ICU lengths of stay more than 3 days would result in an immediate cost savings of only 0.2% of all hospital expenditures for these patients.
Conclusions: Marginal variable ICU costs are relatively small compared with average total costs and are only slightly greater than the cost of a ward day.