Impact of cardiac surgery and neurosurgery patients on variation in severity-adjusted resource use in intensive care units

The resource use of cardiac surgery and neurosurgery patients likely differ from other ICU patients. We evaluated the relevance of these patient groups on overall ICU resource use. Secondary analysis of 69,862 patients in 17 ICUs in Finland, Estonia, and Switzerland in 2015–2017. Direct costs of care were allocated to patients using daily Therapeutic Intervention Scoring System (TISS) scores and ICU length of stay (LOS). The ratios of observed to severity-adjusted expected resource use (standardized resource use ratios; SRURs), direct costs and outcomes were assessed before and after excluding cardiac surgery or cardiac and neurosurgery. Cardiac surgery and neurosurgery, performed only in university hospitals, represented 22% of all ICU admissions and 15–19% of direct costs. Cardiac surgery and neurosurgery were excluded with no consistent effect on SRURs in the whole cohort, regardless of cost separation method. Excluding cardiac surgery or cardiac surgery plus neurosurgery had highly variable effects on SRURs of individual university ICUs, whereas the non-university ICU SRURs decreased. Cardiac and neurosurgery have major effects on the cost structure of multidisciplinary ICUs. Extending SRUR analysis to patient subpopulations facilitates comparison of resource use between ICUs and may help to optimize resource allocation. •Cardiac and neurosurgery, performed exclusively in university hospitals, represented 22% of all ICU admissions and 15–19% of direct costs.•Excluding cardiac surgery and neurosurgery patients did not show any consistent effect on the standardized resource use ratios the whole cohort.•Noteworthy, excluding cardiac surgery and neurosurgery patients decreased the standardized resource use ratios in the non-university ICUs.•The effect of excluding cardiac and neurosurgery on an individual university hospital ICU's standardized resource use ratio varied widely.