Clinical manifestations of adult patients requiring influenza-associated
hospitalization: a prospective multicenter cohort study in Japan via
Background: Influenza remains a clinically heavy burden worldwide.
However, evidence about clinical manifestation has been lacking among
severely ill patients infected with influenza. Methods: The clinical
data for patients who were severely ill with influenza, and required
hospitalization were gathered and analyzed between November 2014 and
August 2019 (5 influenza seasons) using an internet-surveillance system.
Results: A total of 924 patients were enrolled and analyzed. The median
age was 78 years (IQR, 67-84), and the patients in the 2015-2016 season
were significantly younger than those in other seasons. Pneumonia was
the most common disease indicated as a cause for hospitalization,
followed by a poor general condition and exacerbation of underlying
respiratory diseases. Antiviral drugs were administered in 97.0% of the
patients with peramivir being the most-frequently use antiviral.
In-hospital death was recorded for 44 patients (4.8%). Multivariate
analysis indicated that nursing home resident (OR: 6.554) and obesity
(OR: 24.343) were independent predictors of in-hospital mortality.
Conclusion: Complications of influenza infection remain a heavy burden
especially among the elderly. Continuous nationwide surveillance will be
required to grasp the actual situation of influenza epidemics.