Characteristics, Outcomes, and Trends of Patients With COVID-19-Related Critical Illness at a Learning Health System in the United States

Abstract

Background: The coronavirus disease 2019 (COVID-19) pandemic continues to surge in the United States and globally.

Objective: To describe the epidemiology of COVID-19-related critical illness, including trends in outcomes and care delivery.

Design: Single-health system, multihospital retrospective cohort study.

Setting: 5 hospitals within the University of Pennsylvania Health System.

Patients: Adults with COVID-19-related critical illness who were admitted to an intensive care unit (ICU) with acute respiratory failure or shock during the initial surge of the pandemic.

Measurements: The primary exposure for outcomes and care delivery trend analyses was longitudinal time during the pandemic. The primary outcome was all-cause 28-day in-hospital mortality. Secondary outcomes were all-cause death at any time, receipt of mechanical ventilation (MV), and readmissions.

Results: Among 468 patients with COVID-19-related critical illness, 319 (68.2%) were treated with MV and 121 (25.9%) with vasopressors. Outcomes were notable for an all-cause 28-day in-hospital mortality rate of 29.9%, a median ICU stay of 8 days (interquartile range [IQR], 3 to 17 days), a median hospital stay of 13 days (IQR, 7 to 25 days), and an all-cause 30-day readmission rate (among nonhospice survivors) of 10.8%. Mortality decreased over time, from 43.5% (95% CI, 31.3% to 53.8%) to 19.2% (CI, 11.6% to 26.7%) between the first and last 15-day periods in the core adjusted model, whereas patient acuity and other factors did not change.

Limitations: Single-health system study; use of, or highly dynamic trends in, other clinical interventions were not evaluated, nor were complications.

Conclusion: Among patients with COVID-19-related critical illness admitted to ICUs of a learning health system in the United States, mortality seemed to decrease over time despite stable patient characteristics. Further studies are necessary to confirm this result and to investigate causal mechanisms.

Primary funding source: Agency for Healthcare Research and Quality.

Visual Abstract.. COVID-19–Related Critical Illness

In a large health system in the United States, investigators examined whether mortality, receipt of mechanical ventilation, and patient acuity changed over time among adult patients with COVID-19–related critical illness admitted to intensive care units.

Appendix Figure 1.. CONSORT (Consolidated Standards of Reporting Trials) diagram.

ICU = intensive care unit. * 12 patients admitted to the ICU but who did not meet clinical criteria for acute respiratory failure or shock, defined as receiving ≥1 of the following interventions at any time during hospitalization: high-flow nasal cannula with FIo ₂ ≥50%; noninvasive ventilation, including helmet noninvasive ventilation; mechanical ventilation; or vasopressors. † 140 patients died in hospital within 28 days; 15 patients died in hospital after 28 days.

Figure 1.. All-cause 28-day in-hospital mortality over time.

All-cause 28-day in-hospital mortality decreased over ICU admission dates in 15-day periods in the unadjusted (observed), core adjusted, and expanded adjusted models. The core adjusted model includes age, Charlson Comorbidity Index score, SOFA score, and hospital; the expanded adjusted model also includes body mass index, Glasgow Coma Score, oxygen saturation, respiratory rate, platelet count, and Pao2–FIo2 ratio. ICU = intensive care unit; SOFA = Sequential Organ Failure Assessment.

Figure 2.. Patient-level factors over time.

In univariate linear regression models, ICU admission SOFA score (P = 0.141), age (P = 0.41), BMI (P = 0.091), platelet count (P = 0.087), Glasgow Coma Score (P = 0.67), respiratory rate (P = 0.42), oxygen saturation (P = 0.46), and Pao2–FIo2 ratio (P = 0.99) were not associated with ICU admission date. BMI = body mass index; ICU = intensive care unit; SOFA = Sequential Organ Failure Assessment.