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.