Hospital trajectories and early predictors of clinical outcomes differ between SARS-CoV-2 and influenza pneumonia.

Background: A comparison of pneumonias due to SARS-CoV-2 and influenza, in terms of clinical course and predictors of outcomes, might inform prognosis and resource management. We aimed to compare clinical course and outcome predictors in SARS-CoV-2 and influenza pneumonia using multi-state modelling and supervised machine learning on clinical data among hospitalised patients.
Methods: This multicenter retrospective cohort study of patients hospitalised with SARS-CoV-2 (March-December 2020) or influenza (Jan 2015-March 2020) pneumonia had the composite of hospital mortality and hospice discharge as the primary outcome. Multi-state models compared differences in oxygenation/ventilatory utilisation between pneumonias longitudinally throughout hospitalisation. Differences in predictors of outcome were modelled using supervised machine learning classifiers.
Findings: Among 2,529 hospitalisations with SARS-CoV-2 and 2,256 with influenza pneumonia, the primary outcome occurred in 21% and 9%, respectively. Multi-state models differentiated oxygen requirement progression between viruses, with SARS-CoV-2 manifesting rapidly-escalating early hypoxemia. Highly contributory classifier variables for the primary outcome differed substantially between viruses.
Interpretation: SARS-CoV-2 and influenza pneumonia differ in presentation, hospital course, and outcome predictors. These pathogen-specific differential responses in viral pneumonias suggest distinct management approaches should be investigated.
Funding: This project was supported by NIH/NCATS UL1 TR002345, NIH/NCATS KL2 TR002346 (PGL), the Doris Duke Charitable Foundation grant 2015215 (PGL), NIH/NHLBI R35 HL140026 (CSC), and a Big Ideas Award from the BJC HealthCare and Washington University School of Medicine Healthcare Innovation Lab and NIH/NIGMS R35 GM142992 (PS).
Competing Interests: Declaration of interests PGL- Present work: efforts were supported by, BJC HealthCare Healthcare Innovation Lab “Big Ideas” award, Doris Duke Charitable Foundation, and Fund to Retain Clinical Scientists, # 2015215. Outside scope of present work- CDC MMC- Outside scope of present work, grants to institution: DOD PRMRP W81XWH-21-1-0009, NIH/ NIDDK R01-DK126933A -01, NIH/ NIGMS R35-13362546, NIH/NIGMS, R01-GM123193. Patent pending ARCD. P0535US.P2. APM- Outside scope of present work: Pfizer personal stock ownership. TK- Outside scope of present work: Grants: NIA, AHRQ, NLM, NCATS, NIMH; Licenses: Springer, Elsevier; Consultant: Pfizer, Inc; Presentations and Events: Department of Defense. CCS- Outside scope of present work: Grants: NIH, Department of Defense, Roche-Genentech, Quantum Leap Healthcare Collaborative; Consultant: Vasomune, Gen1e Life Sciences, Cellenkos, Janssen. SLW. AD, KD, TMP, SVB, AB, PS, EHG, BNR, MK, and AM have no conflicts of interest to report.
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