Comparison of Body Composition, Physical Capacity, and Immuno-Metabolic Profile in Community-Acquired Pneumonia Caused by COVID-19, Influenza, and Bacteria: A Prospective Cohort Study

Background: Different pathogens can cause community-acquired pneumonia (CAP), however the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) has re-emphasized the important role of respiratory viruses as a cause of CAP. The aim was to explore differences in metabolic profile, body composition, physical capacity, and inflammation between patients hospitalized with CAP caused by different etiology.Methods: A prospective study of Danish patients hospitalized with CAP caused by SARS-CoV-2, influenza, or bacteria. Fat (FM) and fat-free mass (FFM) were assessed with bioelectrical impedance analysis. Physical activity and capacity were assessed using questionnaires and grip strength. Plasma (p)-glucose, p-lipids, hemoglobin A1c (HbA1c), p-adiponectin, and cytokines were measured. Findings: Among 164 patients with CAP, etiology did not affect admission levels of glucose, HbA1c, adiponectin, or lipids. Overall, 15·2% had known diabetes, 6·1% had undiagnosed diabetes, 51·3% had pre-diabetes, 81% had hyperglycemia, and 60% had low HDL-cholesterol, with no difference between groups. Body mass index, FM, and FFM were similar between groups with 73% being abdominal obese, although waist circumference was lower in COVID-19. Physical capacity was similar between groups. More than 80% had low grip strength and low physical activity level. Compared to influenza, COVID-19 had increased levels of interferon (IFN)- , interleukin (IL)-4, IL-5, and IL-6 and increased IFN- and IL-10 compared to bacterial CAP, but no difference in IL-1β, tumor necrosis factor-α, IL-8, IL-18, IL-12p70, C-reactive protein, and adiponectin.Interpretation: Despite higher inflammatory response in COVID-19, metabolic profile, body composition, and functional capacity was similar to patients with influenza and bacterial CAP.Trial Registration: ClinicalTrials.gov (NCT03795662)Funding Statement: Nordsjællands Hospital.Declaration of Interests: The authors declare that they have no conflicts of interests.Ethics Approval Statement: The study was approved by the scientific Ethics Committee at the Capital Region of Denmark (H- 18024256), and conducted in accordance with the Declaration of Helsinki. Oral and written informed consent was obtained from all patients before enrolment.