Investigation of Influenza Cases and Risk Factors Associated with Fatality in Türkiye.

Abstract

Objectives: Influenza is an infectious disease that primarily affects the respiratory system. It can cause high morbidity and mortality, especially in people with risk factors. This study aimed to epidemiologically analyze influenza PCR-positive patients in the 2014-2015 influenza season and to identify risk factors associated with disease severity and fatality.

Methods: Within the scope of national influenza surveillance program, clinical samples from patients with influenza-like illness (ILI) symptoms are sent to the Turkish Public Health Institution, National Influenza Center for testing, accompanied by case information forms. A retrospective analysis was conducted on the case information forms of patients who tested positive for influenza via PCR during the 2014-2015 influenza season. Demographic data were analyzed, and the presence of risk factors associated with fatality was investigated through further analysis.

Results: A total of 1330 patients were included in the study. 684 (51.4%) of the patients were female. The median age was 42.8 years (IQR: 23-61). Among the patients, 154 (11.9%) died. The median age of deceased patients was 60.2 years (IQR: 39.8-75). Being over 65 years old in deceased patients is 3.4 times more likely compared to survived patients [OR=3.4 (95% CI=2.4-4.9)]. Additionally, deceased patients were 4.8 times more likely to have Influenza A (H1N1) compared to survivors [OR=4.8 (95% CI=3.2-7.2)], and the presence of chronic diseases in deceased patients was also 3.4 times higher than in those who survived [OR=3.4 (95% CI=2.3-5.1)].

Conclusion: Infection with H1N1, being elderly and presence of chronic diseases were found to be associated with increased fatality. To mitigate morbidity and mortality, it is crucial to vaccinate individuals with chronic diseases and the elderly, educate them about contact precautions, and encourage prompt healthcare seeking when symptoms appear.