Association between emergency department disposition and mortality in patients with COVID-19 acute respiratory distress syndrome

Abstract

Objectives: Patients hospitalized for COVID-19 frequently develop hypoxemia and acute respiratory distress syndrome (ARDS) after admission. In non-COVID-19 ARDS studies, admission to hospital wards with subsequent transfer to intensive care unit (ICU) is associated with worse outcomes. We hypothesized that initial admission to the ward may affect outcomes in patient with COVID-19 ARDS.

Methods: This was a retrospective study of consecutive adults admitted for COVID-19 ARDS between March 2020 and March 2021 at Stanford Health Care. Mortality scores at hospital admission (Coronavirus Clinical Characterization Consortium Mortality Score [4C score]) and ICU admission (Simplified Acute Physiology Score III [SAPS-III]) were calculated, as well as ROX index for patients on high flow nasal oxygen. Patients were classified by emergency department (ED) disposition (ward-first vs. ICU-direct), and 28- and 60-day mortality and highest level of respiratory support within 1 day of ICU admission were compared. A second cohort (April 2021‒July 2022, n = 129) was phenotyped to validate mortality outcome.

Results: A total of 157 patients were included, 48% of whom were first admitted to the ward (n = 75). Ward-first patients had more comorbidities, including lung disease. Ward-first patients had lower 4C and similar SAPS-III score, yet increased mortality at 28 days (32% vs. 17%, hazard ratio [HR] 2.0, 95% confidence interval [95% CI] 1.0‒3.7, p = 0.039) and 60 days (39% vs. 23%, HR 1.83, 95% CI 1.04‒3.22, p = 0.037) compared to ICU-direct patients. More ward-first patients escalated to mechanical ventilation on day 1 of ICU admission (36% vs. 14%, p = 0.002) despite similar ROX index. Ward-first patients who upgraded to ICU within 48 h of ED presentation had the highest mortality. Mortality findings were replicated in a sensitivity analysis.

Conclusion: Despite similar baseline risk scores, ward-first patients with COVID-19 ARDS had increased mortality and escalation to mechanical ventilation compared to ICU-direct patients. Ward-first patients requiring ICU upgrade within 48 h were at highest risk, highlighting a need for improved identification of this group at ED admission.

Keywords: COVID‐19; acute respiratory distress syndrome; disposition; emergency department.

FIGURE 1

Study design and patient selection. All patients (n = 382) with a positive SARS‐CoV‐2 test who were admitted to medical intensive care unit (ICU) between March 2020 and March 2021 were screened. Patients (n = 134) with incidental infections or transferred from outside hospitals without emergency department (ED) admission data were excluded. Patients who did not meet criteria for acute respiratory distress (ARDS) (n = 72) or who did not receive steroids (n = 19) were excluded. Patients were classified either as ward‐first (n = 75) or ICU‐direct (n = 82) based on initial admission location.

FIGURE 2

Admission to intensive care unit (ICU) was associated with reduced mortality in patients who developed COVID‐19‐associated acute respiratory distress syndrome (ARDS). The (A) 28‐day and (B) 60‐day survival rates were worse in ward‐first (n = 75) patients who developed COVID‐19 ARDS as compared to ICU‐direct patients (n = 82). CI, confidence interval; HR, hazards ratio.

FIGURE 3

Ward‐first patients required more rapid escalation to mechanical ventilation within 1 day of intensive care unit (ICU) admission compared to ICU‐direct patients. (A) At time of ICU admission, a greater percentage of ICU‐direct patients (n = 16 out of 82, 20%) required mechanical invasive ventilation (MIV) as compared to ward‐first patients (n = 1 out of 75, 1%). However, more ward‐first patients (n = 27 out of 74, 36%) who were admitted to the ICU on high flow nasal oxygen (HFNO) or non‐invasive ventilation (NIV, inclusive of continuous positive airway pressure and bilevel positive airway pressure) progressed to requiring MIV within 1 day compared to ICU‐direct patients (n = 9 out of 66 patients, 14%). More ward‐first patients progressed to MIV on day 2 of ICU admission compared to ICU‐direct patients; however, this was not statistically significant. (B) Sankey diagrams illustrate progression of respiratory support needs for ward‐first (left) and ICU‐direct (right) patients at ICU admission and days 1 and 2 of ICU stay. NC, nasal cannula.

FIGURE 4

Shorter duration between hospital admission and upgrade to intensive care unit (ICU) was associated with worse 28‐day mortality in patients who developed acute respiratory distress syndrome (ARDS). The (A) 28‐day and (B) 60‐day survival curves in ward‐first patients (n = 75) who developed COVID‐19 ARDS and required upgrade to ICU in less than 2 days (n = 25) compared with patients who upgraded 2 days or later (n = 50) after admission. ICU‐direct survival curve was included for reference. CI, confidence interval; HR, hazards ratio.