In-Hospital Death and Risk Factors in Adults With Influenza in Spain (2016-2022): A Cross-Sectional Study With Focus on Older Patients.

Background and Aims: Influenza mortality rates varying across different populations. This study aims to assess influenza lethality in hospitalized adults (≥ 15 years) and identify key risk factors according to age. Methods: We designed a retrospective study at Dr. Balmis General University Hospital (Alicante, Spain), including patients hospitalized for influenza from 2016 to 2022. In-hospital death was expressed as the case fatality rate (CFR). Variables yielding a Results: Of 1613 patients admitted for influenza (incidence 86 per 10,000 admissions), 96 died (CFR 5.95%). Lethality increased with age, reaching 8.4% in patients aged 80-89 years and 19.5% in those over 90. In all of the cohort, risk factors were age, dementia, respiratory failure, influenza pneumonia, and sepsis, while treatment with oseltamivir acted as a protective factor. In patients < 80 years of age, risk factors were neoplasia, respiratory failure, and influenza pneumonia, whereas oseltamivir treatment was a protective factor. In patients 80 years ( Conclusion: Influenza deaths increase with age; this relationship is accentuated in people aged 80 or older. Respiratory failure was the main risk factor in all patients hospitalized for influenza. Treatment with oseltamivir protected patients (especially those < 80 years) against deaths. Patients < 80 years-old carried a higher risk of death if they had a neoplasia, whereas in ≥ 80 patients, the risk was associated with dementia and noninfluenza pneumonia.