Methods

The current study was conducted on all PCR-positive H1N1 patients hospitalized at Imam Khomeini Hospital, Tehran, Iran, from 21 March to 21 September 2019. The sample size was calculated as 64. After obtaining all due permission, records of PCR-positive patients with H1N1 influenza were retrieved and searched.
For this cross-sectional study, inclusion criteria were H1N1 influenza cases confirmed by the PCR test between 21 March and 21 September 2019. Exclusion criteria were incomplete or missing clinical information and laboratory and imaging records. All information, including demographic data, clinical presentations, prescribed medicines, and imaging and laboratory records, were retrieved and recorded in a questionnaire. Demographic data, age and gender, and the history of other coexisting diseases were retrieved and recorded. Influenza risk factors were defined according to the Mendel textbook of Infectious diseases. The information regarding commonly used immunosuppressive medications and drugs used in the emergency department and infectious diseases wards were also extracted from credible reference books.
All patient records of the clinical presentations (cough, sputum, dyspnea, orthopnea, hemoptysis, fever, and chills) were extracted from the files and recorded. Vital signs, including oxygen saturation, systolic and diastolic blood pressure, pulse rate, respiratory rate, and temperature, were also retrieved and recorded.
The information regarding laboratory test results, including WBC, Hb, plat, ESR, CRP, ALP, ALT, and AST, were also recorded in the data sheets. The CT scan imaging records of the patients were also extracted and compiled. This information included the number of involved lung lobes, axial location, anteroposterior location, shape, and pattern of the lesion, margin, and other lesion characteristics. Disease outcomes regarding survival or death were also extracted and included. The imaging procedure was carried out using a Siemens Emotion 6 Slice CT Scanner at Imam Khomeini Hospital’s facility.
The data gathering instrument was a questionnaire designed according to the data needed for the study. This questionnaire contained demographic data, clinical presentations, laboratory findings, CT scan reports, and the outcomes of the diseases.
The research ethics board of the hospital approved the study. The need for a priori informed consent was waived due to the noninterventional study design. Private information of the patients was kept confidential by the researchers, and it was set that if the data needed to be reproduced, this should be done with the permission of the hospital ethics committee.
Data were analyzed using the SPSS software version 22. In the descriptive analysis, quantitative variables were reported with median and interquartile range and qualitative variables with number and percentage. The analytical part assessed the relationship between the disease outcomes and vital signs and laboratory findings with the Mann-Whitney U test. The Chi-Square test was used to examine the relationship between disease outcome and clinical symptoms, risk factors, and imaging findings. In the multivariable logistic regression, using the Enter method, the outcome of the disease was determined according to the influential and significant parameters, and the results were reported as odds ratios (OR) with a 95% confidence interval.