Prognostic Factors for 30-Day Mortality in Critically Ill Patients With Coronavirus Disease 2019

An Observational Cohort Study

Paloma Ferrando-Vivas, BSc; James Doidge, PhD; Karen Thomas, MSc; Doug W. Gould, PhD; Paul Mouncey, MSc; Manu Shankar-Hari, PhD; J. Duncan Young, DM; Kathryn M. Rowan, PhD; David A. Harrison, PhD

Disclosures

Crit Care Med. 2021;49(1):102-111. 

In This Article

Abstract and Introduction

Abstract

Objectives: To identify characteristics that predict 30-day mortality among patients critically ill with coronavirus disease 2019 in England, Wales, and Northern Ireland.

Design: Observational cohort study.

Setting: A total of 258 adult critical care units.

Patients: A total of 10,362 patients with confirmed coronavirus disease 2019 with a start of critical care between March 1, 2020, and June 22, 2020, of whom 9,990 were eligible (excluding patients with a duration of critical care less than 24 hr or missing core variables).

Measurements and Main Results: The main outcome measure was time to death within 30 days of the start of critical care. Of 9,990 eligible patients (median age 60 yr, 70% male), 3,933 died within 30 days of the start of critical care. As of July 22, 2020, 189 patients were still receiving critical care and a further 446 were still in acute hospital. Data were missing for between 0.1% and 7.2% of patients across prognostic factors. We imputed missing data ten-fold, using fully conditional specification and continuous variables were modeled using restricted cubic splines. Associations between the candidate prognostic factors and time to death within 30 days of the start of critical care were determined after adjustment for multiple variables with Cox proportional hazards modeling. Significant associations were identified for age, ethnicity, deprivation, body mass index, prior dependency, immunocompromise, lowest systolic blood pressure, highest heart rate, highest respiratory rate, PaO 2/FIO 2 ratio (and interaction with mechanical ventilation), highest blood lactate concentration, highest serum urea, and lowest platelet count over the first 24 hours of critical care. Nonsignificant associations were found for sex, sedation, highest temperature, and lowest hemoglobin concentration.

Conclusions: We identified patient characteristics that predict an increased likelihood of death within 30 days of the start of critical care for patients with coronavirus disease 2019. These findings may support development of a prediction model for benchmarking critical care providers.

Introduction

Coronavirus disease 2019 (COVID-19) can result in severe illness requiring critical care in around 5% of those with confirmed infection.[1] Reported mortality for patients critically ill with COVID-19 has varied widely;[2–6] however, prognostic research has been focused on models for identifying people in the general population at risk of being admitted to hospital with COVID-19, detecting likely COVID-19 in patients with suspected infection, and predicting prognosis of hospitalized patients with COVID-19.[7] Patients critically ill with COVID-19 have not been the focus of many prognostic studies, despite their increased risk of death compared with patients outside of critical care. Most studies have been based on small samples and few have considered data from countries outside China.

Since the outbreak in the United Kingdom (UK) started, the Intensive Care National Audit & Research Centre has been collecting data from critical care units participating in the Case Mix Programme (the national clinical audit covering all NHS adult, general intensive care, and combined intensive care/high dependency units in England, Wales, and Northern Ireland, plus some additional specialist and non-NHS critical care units) to support the NHS and policy makers with rapid data collection and analysis. The number of patients included and completeness of the population coverage make the Case Mix Programme an ideal resource to investigate factors associated with mortality in critical care. At the peak of the epidemic, 400 patients per day were being admitted to critical care with COVID-19,[8] exceeding the typical number of daily unplanned admissions to adult general critical care in the UK for all conditions combined.

The aim of the present study was to identify patient characteristics that predict death in hospital within 30 days of the start of critical care for patients critically ill with confirmed COVID-19 in England, Wales, and Northern Ireland.

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