The University of Louisville Journal of Respiratory Infections


The author(s) received no specific funding for this work.


Introduction: There is substantial variation in the clinical characteristics and outcomes of severe coronavirus disease (COVID-19), making it difficult to do an optimal assessment of this condition. We reviewed the current English literature to identify the findings concerning the baseline characteristics and health outcomes of patients with severe COVID-19, primarily those with acute respiratory distress syndrome (ARDS).

Methods: We examined only studies that assessed patients with confirmed COVID-19 by reverse transcription-polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) with at least one of the following severity criteria: treated in the intensive care unit (ICU), ARDS, and/or invasive mechanical ventilation (IMV) treatment. We assessed the quality of the studies according to the National Heart, Lung and Blood Institute study quality assessment tools.

Results: Seven of 39 studies fulfilled the inclusion criteria. These seven studies included a total 1,863 patients; the median age was 63.5 years (range 49–70). A total 370 (19.8%) were females. Four studies were from the USA, two from China and one from Italy. Comorbidities were reported in six studies. Fever was reported in five studies and was present in 159 out of 272 patients. Cough and shortness of breath (SOB) were reported in four studies, present in 111 out of 142 and 100 out of 142 patients, respectively. The median total lymphocytes was reported in five studies with a range of 400–889/ul. IMV ranged from 15% to 100%, and mortality ranged from 14.6% to 88%. In a subgroup analysis by country, patients from the US showed more comorbidities and higher percentages of IMV and mortality. The mean assessment quality score of the seven studies was 5 out of a maximum 9.

Conclusions: Severe COVID-19 was predominantly seen in male patients who were 60 years or older and was associated with comorbidities. Most of the patients were admitted to the ICU and needed IMV support due to ARDS, and the overall mortality rate had a range of 14.6–88%.



Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.