Early Clinical Deterioration Among Emergency Department Boarders: A Retrospective Analysis

To define the incidence and identify factors associated with early clinical deterioration among patients boarding in the emergency department (ED).

We conducted a retrospective study of adult ED patients admitted to internal medicine or medicine subspecialty services at a floor level of care who boarded between 4 and 48 hours within a 5-hospital academic health system from January 2018 to June 2024. Early deterioration was any escalation from floor to intermediate or intensive level of care within 48 hours of admission order. Logistic regression models were employed to estimate adjusted odds ratios (aOR). Covariates included boarding time, demographics, comorbidities, vital signs, laboratory values, ED and hospital census, overnight admission, and socioeconomic status.

Among 173,168 consecutive encounters meeting enrollment criteria, 6,299 (3.6%) experienced deterioration; 2,823 (45%) occurred while still in the ED. Median boarding time was 12.5 hours (interquartile range [IQR]: 8.2 to 20.7 hours) for those with deterioration versus 10.2 hours (IQR: 6.9 to 18.3) for those without. Boarding duration was associated with deterioration both overall (aOR: 1.17, 95% confidence interval [CI] 1.10 to 1.24) and deterioration occurring in the ED (aOR 1.58, 95% CI 1.46 to 1.71) with a 0.8% and 2.4% increased relative risk for each excess hour of boarding, respectively. Other independent predictors included care at an academic safety-net hospital (aOR 2.41; 95% CI 2.17 to 2.67), overnight admission (aOR 1.29; 95% CI 1.21 to 1.38), and elevated lactate (aOR 1.93; 95% CI 1.72 to 2.17). The 28-day mortality rate was higher in patients experiencing deteriorations (13.0% vs 3.9%, OR 3.66, 95% CI 3.38 to 3.96).

Early clinical deterioration occurs with a meaningful frequency among ED boarders. Boarding duration was independently associated with increased odds of early clinical deterioration, an event known to increase morbidity and mortality. These data underscore the considerable patient safety risks inherent to boarding.