Comparison of Hospitalized Coronavirus Disease 2019 and Influenza Patients Requiring Supplemental Oxygen in a Cohort Study: Clinical Impact and Resource Consumption.

Background: To compare clinical characteristics, outcomes, and resource consumption of patients with coronavirus disease 2019 (COVID-19) and seasonal influenza requiring supplemental oxygen.
Methods: Retrospective cohort study conducted at a tertiary-care hospital. Patients admitted because of seasonal influenza between 2017 and 2019, or with COVID-19 between March and May 2020 requiring supplemental oxygen were compared. Primary outcome: 30-day mortality. Secondary outcomes: 90-day mortality and hospitalization costs. Attempted sample size to detect an 11% difference in mortality was 187 patients per group.
Results: COVID-19 cases were younger (median years of age, 67; interquartile range [IQR] 54-78 vs 76 [IQR 64-83]; P < .001) and more frequently overweight, whereas influenza cases had more hypertension, immunosuppression, and chronic heart, respiratory, and renal disease. Compared with influenza, COVID-19 cases had more pneumonia (98% vs 60%, <.001), higher Modified Early Warning Score (MEWS) and CURB-65 (confusion, blood urea nitrogen, respiratory rate, systolic blood pressure, and age >65 years) scores and were more likely to show worse progression on the World Health Organization ordinal scale (33% vs 4%; P < .001). The 30-day mortality rate was higher for COVID-19 than for influenza: 15% vs 5% (P = .001). The median age of nonsurviving cases was 81 (IQR 74-88) and 77.5 (IQR 65-84) (P = .385), respectively. COVID-19 was independently associated with 30-day (hazard ratio [HR], 4.6; 95% confidence interval [CI], 2-10.4) and 90-day (HR, 5.2; 95% CI, 2.4-11.4) mortality. Sensitivity and subgroup analyses, including a subgroup considering only patients with pneumonia, did not show different trends. Regarding resource consumption, COVID-19 patients had longer hospital stays and higher critical care, pharmacy, and complementary test costs.
Conclusions: Although influenza patients were older and had more comorbidities, COVID-19 cases requiring supplemental oxygen on admission had worse clinical and economic outcomes.
Competing Interests: Potential conflicts of interest. I. L. M. reports Rio Hortega Grant Instituto Carlos III CM18/00047 from January 2018 to December 2020, unrelated to this work; and support by Pfizer and Angelini to attend meetings (no payment to author; registration to meetings only). I. A. A. reports Rio Hortega Grant Instituto Carlos III, unrelated to this work. L. S. reports payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Pfizer, Angelini, and Menarini. R. G. F. reports grants or contracts unrelated to this work: FIS ISCIII PI19/00019; honoraria for lectures and presentations from Gilead Inc, MSD, GSK; and participation on GC2010 DSMB Interim Safety Data Review. S. C. reports support by Pfizer, Angelini, and MSD to attend meetings (no payments to author; registration to meetings only). J. G. J. reports support by Pfizer, Angelini, and MSD to attend meetings (no payments to author; registration to meetings only). X. N. reports payment or honoraria for Amgen UCB lectures; support for attending meetings and/or travel from Amgen, Lilly; and participation on a Data Safety Monitoring Board or Advisory Board for Amgen UCB. S. G. Z. reports grants or contracts unrelated to this study: FIS ISCIII PI21/00509, Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC). J. P. H. reports honoraria for lectures from Pfizer, Angelini, Menarini, and MSD; and participation on advisory boards for Menarini, MSD, and GILEAD. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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