Effect of Emergency Department and ICU Occupancy on Admission Decisions and Outcomes for Critically Ill Patients

Abstract

Objectives: ICU admission delays can negatively affect patient outcomes, but emergency department volume and boarding times may also affect these decisions and associated patient outcomes. We sought to investigate the effect of emergency department and ICU capacity strain on ICU admission decisions and to examine the effect of emergency department boarding time of critically ill patients on in-hospital mortality.

Design: A retrospective cohort study.

Setting: Single academic tertiary care hospital.

Patients: Adult critically ill emergency department patients for whom a consult for medical ICU admission was requested, over a 21-month period.

Interventions: None.

Measurements and main results: Patient data, including severity of illness (Mortality Probability Model III on Admission), outcomes of mortality and persistent organ dysfunction, and hourly census reports for the emergency department, for all ICUs and all adult wards were compiled. A total of 854 emergency department requests for ICU admission were logged, with 455 (53.3%) as "accept" and 399 (46.7%) as "deny" cases, with median emergency department boarding times 4.2 hours (interquartile range, 2.8-6.3 hr) and 11.7 hours (3.2-20.3 hr) and similar rates of persistent organ dysfunction and/or death 41.5% and 44.6%, respectively. Those accepted were younger (mean ± SD, 61 ± 17 vs 65 ± 18 yr) and more severely ill (median Mortality Probability Model III on Admission score, 15.3% [7.0-29.5%] vs 13.4% [6.3-25.2%]) than those denied admission. In the multivariable model, a full medical ICU was the only hospital-level factor significantly associated with a lower probability of ICU acceptance (odds ratio, 0.55 [95% CI, 0.37-0.81]). Using propensity score analysis to account for imbalances in baseline characteristics between those accepted or denied for ICU admission, longer emergency department boarding time after consult was associated with higher odds of mortality and persistent organ dysfunction (odds ratio, 1.77 [1.07-2.95]/log10 hour increase).

Conclusions: ICU admission decisions for critically ill emergency department patients are affected by medical ICU bed availability, though higher emergency department volume and other ICU occupancy did not play a role. Prolonged emergency department boarding times were associated with worse patient outcomes, suggesting a need for improved throughput and targeted care for patients awaiting ICU admission.

Figure. Predicted probability of Persistent Organ Dysfunction + Death (POD+D) by Emergency Department (ED) boarding time (hours)

In this cohort of critically ill ED patients for whom Medical Intensive Care Unit admission consult was completed, between 10/2013 and 06/2015, ED boarding time post-consult is associated with an increase in the odds of dying or having significant morbidity during the hospitalization. The POD+D model was adjusted for age, gender, race, insurance, nursing home/facility pre-hospital origin, interaction between age and nursing home origin, MPM₀-III score, nightshift timing of consult, critical care diagnosis category, hospital LOS, and ICU admission decision/propensity score quintile.