Predictors of Early and Long-term Mortality After Icu Discharge in Critically Ill Covid-19 Patients: a Prospective Cohort Study

Mariana M. S. Santos, Isabel J. Pereira, Nelson Cuboia, Joana Reis-Pardal, Diana Adrião, Teresa Cardoso, Irene Aragão, Lurdes Santos, António Sarmento, Regis G. Rosa, Cristina Granja, Cassiano Teixeira, Luís Azevedo


To mitigate mortality among critically ill COVID-19 patients, both during their Intensive Care Unit (ICU) stay and following ICU discharge, it is crucial to measure its frequency, identify predictors and to establish an appropriate post-ICU follow-up strategy.


Critically ill COVID-19 patients present greater need for life-sustaining treatments, high mortality, and prolonged length of intensive care unit (ICU) stay [1]. In-hospital mortality can reach 31% and is expected that as much as 76% of patients will require invasive mechanical ventilation (IMV) [2]. Worst long-term sequelae are also expected for ICU COVID-19 survivors, although the one-year mortality following ICU discharge appears to be influenced more by patient’s comorbidities rather than the severity of COVID-19 pneumonia itself [3].

Materials and method

We conducted a 12-month prospective multicentre cohort study, assessing a large sample of critical COVID-19 patients, admitted in 3 ICU from three tertiary hospitals at North Portugal. Participant hospitals were public and two of them were academic. The recruitment occurred from May 30, 2020, to July 31, 2021. The study included patients admitted to the ICU from March 1st, 2020, to July 31, 2021, and the follow up period ended on August 31, 2022. Medical records were accessed solely for research purposes during the study period, and only the authors had access to information that could potentially identify individual participants. Participant information was included in the study database using unique codes as a means to safeguard all personal data.


From May 2020 to July 2021, 601 COVID patients admitted to the ICU were screened and 586 met eligibility criteria and were enrolled in the study. 468 patients survived after ICU admission and were included in the 12-month follow-up cohort. Among the 586 patients enrolled, 155 (26.5%) died before completing 1 year of follow-up and of these, 118 patients (20.1%) died in the ICU and 37 (6.4%) patients died after ICU discharge. Amongst the 468 patients eligible for the 1-year follow-up, which was completed on August 16, 2022, all patients were assessed.


In the present cohort study, performed in adult critically ill patients with COVID-19 admitted to the ICU and followed up during the first 12 months after ICU discharge, we observed an ICU mortality of 20.1%, which is inferior to previous studies where the reported mortality ranged between 30 to 65% [12–14]. Moreover, regarding ICU survivors, early mortality, considering 30 days after ICU discharge, was 5.3% and late mortality (from day 31 to day 365) was 2.6%; thus, the overall 1-year mortality observed among ICU survivors was 7.9% and the overall 1-year mortality among all the COVID-19 patients admitted to the ICU was 26.5%.


By reporting on the early and late mortality post-ICU discharge in critically ill COVID-19 patients, we have shown that there is a period immediately following ICU discharge, specifically in the first 30 days, with a higher mortality rate, but this risk decreases over time up to 1 year. Therefore, it is crucial to closely monitor critically ill COVID-19 patients who have survived intensive care, particularly those with pre-existing comorbidities, to prevent adverse outcomes and mortality, as our findings indicate that pre-ICU comorbidities were the sole factors associated with mortality after ICU discharge. Since we identified a limited number of previous studies, further research is urgently needed on post-ICU mortality rates and to establish an appropriate post-ICU follow-up strategy for surviving critically ill COVID-19 patients.

Citation: Santos MMS, Pereira IJ, Cuboia N, Reis-Pardal J, Adrião D, Cardoso T, et al. (2023) Predictors of early and long-term mortality after ICU discharge in critically ill COVID-19 patients: A prospective cohort study. PLoS ONE 18(11): e0293883.

Editor: Chiara Lazzeri, Azienda Ospedaliero Universitaria Careggi, ITALY

Received: July 26, 2023; Accepted: October 23, 2023; Published: November 2, 2023

Copyright: © 2023 Santos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data can be found within the paper and Supporting Information files. Data privacy regulations prohibit deposition of individual level data to public repositories and the ethical approval does not cover public sharing of data for unknown purposes. Upon contact with the authors and ethics committee of the participant hospitals (, an institutional data transfer agreement may be established, and data shared if the aims of data use are covered by ethical approval and patient consent.

Funding: This study was funded by a research grant (PD/BD/150529/2019) from the Portuguese foundation FCT (Fundação para a Ciência e a Tecnologia). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors of this manuscript have the following competing interests: Mariana M S Santos acknowledges having been awarded a research grant (PD/BD/150529/2019) from Fundação para a Ciência e a Tecnologia (FCT). Regis G Rosa discloses research grants from Pfizer and lecture fees from Novartis, both unrelated to the work submitted herein. This does not alter our adherence to PLOS ONE policies on sharing data and materials. The remaining authors have no competing interests to disclose.


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