Introduction
Viral infectious diseases have become of great concern in recent years.
Every year, novel viruses emerge, and the existing ones become more
resistant. The influenza virus is one of the most common infectious
microorganisms, which is classified into four strains A, B, C, and
D.[1] Influenza A and B viruses are the most important ones, and the
C and D strain almost exclusively infect animals.[2] Influenza A
virus is a member of the Orthomyxoviridae family, which is classified
into 16 HA subtypes (H1–H16) and 9 NA subtypes (N1–N9) based on the
haemagglutinin (HA) and neuraminidase (NA) molecules on their
surfaces.[3] Influenza viruses with new HA subtypes can cause
widespread epidemics and global pandemics.[4]
Most diseases caused by the H1N1 virus are acute and spontaneously
resolve, and children and young adults are most commonly
inflicted.[5] It is postulated that the low attack rate amongst the
elderly can be due to their multiple exposures to influenza viruses
which leads to the development of cross-protective antibodies.[6]
The overall case fatality rate has been reported as less than 0.5%, and
most serious cases are usually children and nonelderly adults;
approximately 90% of deaths have occurred in individuals younger than
65.[4, 7]
A significant proportion of hospitalization or death due to H1N1
influenza occurs amongst those with no concurrent illnesses.[8]
However, several risk factors exist for severe H1N1 influenza. Different
studies have demonstrated that the main risk factors for severe Illness,
complications, hospitalization, or death attributable to H1N1 influenza
include young age, pregnancy, chronic cardiovascular condition, chronic
lung disorders, metabolic disorders, neurologic conditions,
immunosuppression, obesity, hemoglobinopathies, chronic renal disease,
and chronic hepatic disease.[9]
The main pathological changes in patients with H1N1 influenza are focal
to extensive diffuse alveolar damage (DAD) in the lungs.[10] The
most common technique for the primary evaluation of patients with H1N1
influenza is serial chest radiography.[11] However, it is
demonstrated that multislice CT (MSCT) scanning can be more sensitive
and provide detailed information. Several studies have reported that the
predominant CT findings of the disease are unilateral or bilateral
multifocal or subpleural ground-glass opacities (GGOs) with or without
consolidation.[12] These patients’ most common CT findings in the
first week are reported to be ground-glass opacities with or without
consolidation. Subsequently, the lesions progress in the second week and
substantially resolve in 4 weeks. Moreover, fibrosis develops in the
first week, peaks in the infection’s third week, and slowly decreases.
Air trappings can also be noted.[11]
Prediction of the progress of the disease and timely intervention can
facilitate the timely management of the patients. Although risk factors,
clinical manifestations, and imaging findings associated with H1N1
influenza have been reported in several studies, they have not been
systematically assessed as predictors of severe disease or death. The
current study investigated the relationship between clinical
manifestations, laboratory findings, imaging reports, and malignant
outcomes of the infection with H1N1 influenza.