Comparison of Hospitalized Patients With ARDS Caused by COVID-19 and H1N1

Abstract

Background: Since the outbreak of coronavirus disease 2019 (COVID-19) in China in December 2019, considerable attention has been focused on its elucidation. However, it is also important for clinicians and epidemiologists to differentiate COVID-19 from other respiratory infectious diseases such as influenza viruses.

Research question: The aim of this study was to explore the different clinical presentations between COVID-19 and influenza A (H1N1) pneumonia in patients with ARDS.

Study design and methods: This analysis was a retrospective case-control study. Two independent cohorts of patients with ARDS infected with either COVID-19 (n = 73) or H1N1 (n = 75) were compared. Their clinical manifestations, imaging characteristics, treatments, and prognosis were analyzed and compared.

Results: The median age of patients with COVID-19 was higher than that of patients with H1N1, and there was a higher proportion of male subjects among the H1N1 cohort (P < .05). Patients with COVID-19 exhibited higher proportions of nonproductive coughs, fatigue, and GI symptoms than those of patients with H1N1 (P < .05). Patients with H1N1 had higher Sequential Organ Failure Assessment (SOFA) scores than patients with COVID-19 (P < .05). The Pao₂/Fio₂ of 198.5 mm Hg in the COVID-19 cohort was significantly higher than the Pao₂/Fio₂ of 107.0 mm Hg in the H1N1 cohort (P < .001). Ground-glass opacities was more common in patients with COVID-19 than in patients with H1N1 (P < .001). There was a greater variety of antiviral therapies administered to COVID-19 patients than to H1N1 patients. The in-hospital mortality of patients with COVID-19 was 28.8%, whereas that of patients with H1N1 was 34.7% (P = .483). SOFA score-adjusted mortality of H1N1 patients was significantly higher than that of COVID-19 patients, with a rate ratio of 2.009 (95% CI, 1.563-2.583; P < .001).

Interpretation: There were many differences in clinical presentations between patients with ARDS infected with either COVID-19 or H1N1. Compared with H1N1 patients, patients with COVID-19-induced ARDS had lower severity of illness scores at presentation and lower SOFA score-adjusted mortality.

Keywords: ARDS; COVID-19; H1N1; influenza A; mortality.

Figure 1

A-D, Imaging characteristics of chest CT scans from patients with coronavirus disease 2019 (COVID-19) and influenza A (H1N1) . A, A 60-year-old man with COVID-19 exhibited multiple ground-glass opacities in both lungs. B, A 75-year-old man with COVID-19 exhibited diffuse ground-glass opacities in both lungs. C, A 46-year-old woman with H1N1 exhibited exudation and consolidation distributed with bronchus in multiple lobes and segments. D, A 66-year-old man with H1N1 exhibited ground-glass opacities with little exudation and consolidation distributed diffusely in both lungs.

Figure 2

Multivariate model of the specific risk factors for COVID-19 or H1N1. Plots reporting variables independently associated with the risk for COVID-19 or H1N1 in the final model, with their 95% CIs. APACHE = Acute Physiology and Chronic Health Evaluation; AST = aspartate transaminase; SOFA = sequential organ failure assessment. See Figure 1 legend for expansion of other abbreviations.