COVID-19 vs H1N1 Influenza: A Clinical Characteristic Comparison

Hospitalized patients with coronavirus disease 2019 (COVID-19) exhibited higher proportions of nonproductive cough, fatigue, and gastrointestinal symptoms as well as lower severity of illness scores than patients with H1N1 influenza, according to study results published in CHEST.

Demographic and clinical information was collected from patients with confirmed COVID-19 with acute respiratory distress syndrome (ARDS) hospitalized in Wuhan, China, and retrospectively compared with data collected from hospitalized patients with H1N1 influenza who also had ARDS. 

A total of 79 patients with confirmed COVID19 and 75 patients with confirmed H1N1 influenza who were also experiencing ARDS. The median age of patients with COVID-19 patients was older (67 vs 52 years; P <.00) and less likely to be men compared with patients with H1N1 (61.5% vs 80.0%; P =.011). Furthermore, 31.5% of patients with COVID-19 had a history of cardiovascular disease compared with 10.7% in patients with H1N1 influenza (P =.002).

In addition, patients with COVID-19 had higher instances of septic shock, but sequential organ failure assessment (SOFA) scores were lower than in those with H1N1 influenza (2 vs 5; P <.001). Instances of fatigue, myalgia, and gastrointestinal symptoms in patients with COVID-19 (63.0%, 37.0%, and 34.2%, respectively) were higher than in those with H1N1 influenza (18.7%, 6.7%, and 14.7%, respectively). Additionally, the median partial pressure of oxygen (PaO2)/fractional inspired oxygen (FiO2) was significantly higher than in patients with H1N1 influenza (198.2 mm Hg vs 107.0 mm Hg).  

Study limitations included the retrospective design and the condition of patients with H1N1 influenza was more severe compared with those with COVID-19, which may have led to statistical disequilibrium. Importantly, more than a third of patients with COVID-19 were still hospitalized at the time of manuscript submission, meaning that the actual mortality rate was likely higher.

“[W]e found that ground-glass opacity was more common in COVID-19 patients than in H1N1 patients, whereas consolidation was more frequent in H1NI patients,” the researchers wrote. “In addition to diffuse alveolar damage in pathological findings in lungs indicating ARDS, COVID-19 is accompanied by cellular fibromyxoid exudates while H1N1 is accompanied by necrotizing bronchiolitis and extensive hemorrhage. Therefore, these differential pathological changes may present as distinguishing imaging characteristics during clinical assessments.”

Reference

Tang X, Du R, Wang R, et al. Comparison of hospitalized patients with acute respiratory distress syndrome caused by COVID-19 and H1N1 [published March 26, 2020]. CHEST. doi:10.1016/j.chest.2020.03.032

This article originally appeared on Pulmonology Advisor