Demographic Differences in COVID-19 vs Non-COVID-19 Severe Pneumonia

microscopic pneumonia in lungs
microscopic pneumonia in lungs
In patients with severe pneumonia, how do clinical characteristics, comorbidities, and mortality rates differ between those with vs without COVID-19?

A recent study found no differences in mortality between patients hospitalized in an intensive care unit (ICU) with severe COVID-19 pneumonia and those in an ICU with severe non–COVID-19 pneumonia. Study findings were published in The Clinical Respiratory Journal.

Recognizing the rarity of comparisons of patients in an ICU setting with severe SARS-CoV-2 pneumonia vs those with other seasonal/nonseasonal severe viral infections, researchers for the current study sought to compare patient-specific demographic variables (ie, age, ethnicity, obesity, comorbidities); duration of illness; ICU organ supportive measures; and outcomes between the patients in the ICU with severe pneumonia related to COVID-19 vs similar patients without COVID-19. 

The retrospective cohort study was conducted among patients older than18 years of age admitted to the ICU at University Hospital Southampton, United Kingdom, with a diagnosis of COVID-19 between March 2020 and June 2020, or with a diagnosis of viral pneumonia between January 2019 and December 2019. A total of 93 patients with COVID-19 who were admitted to the ICU for respiratory support (COVID-19 cohort) and 52 ICU-hospitalized individuals with non–SARS-CoV-2 viral pneumonia (historical cohort) were enrolled in the study.

Investigators found that the median onset of symptoms was shorter among those with non–COVID-19 viral pneumonia than those with COVID-19. Further, a statistically significant increased percentage of obesity (ie, body mass index >30 kg/m2) was reported in the COVID-19 cohort vs the historical cohort (41.9% vs 22.6%, respectively; P =.02). The COVID-19 cohort also included significantly more patients of non-White ethnicity (41.0% vs 6.0%; P <.001) and diabetes (30.0% vs 13.2%; P =.03). Notably, the COVID-19 group also had a significantly lower prevalence of chronic obstructive pulmonary disease (COPD)/asthma than the historical cohort (16.1% vs 34.0%; P =.02).

Additionally, the neutrophil-to-lymphocyte ratio was significantly lower in the COVID-19 vs historical cohort (6.7 vs 10.0, respectively; P =.006). Moreover, the use of mechanical ventilation was significantly more common among those in the COVID-19 group vs the historical group (58.1% vs 26.4%, respectively; P <.001). Although no significant differences in mortality were reported between the groups, length of ICU stay (8 days vs 4 days, respectively; P <.001) and length of hospital stay (22 days vs 11 days, respectively; P <.001) were both prolonged in the COVID-19 vs the historical cohort.

Of note, the most common pathogens reported among those in the historical cohort were rhinovirus and influenza A (26% for each).

A major limitation of the current study is its single-center, retrospective design and the fact that it was conducted in a small group of patients.

The researchers concluded that additional studies with larger sample sizes are warranted to permit further evaluation of clinical parameters in these patients.


Dadhwal K, Stonham R, Breen H, Poole S, Saeed K, Dushianthan A. Severe COVID-19 pneumonia in an intensive care setting and comparisons with historic severe viral pneumonia due to other viruses. Clin Respir J. Published online February 24, 2022. doi:10.1111/crj.13482