Impact and characteristics of hospital-acquired influenza over 10 seasons in a third-level university hospital

Objectives: To analyze the characteristics of patients with nosocomial flu, to compare them with patients with community-acquired influenza to study possible differences and to identify possible risk factors associated with this type of flu.Patients and methods: Observational, cross-sectional and retrospective study of hospitalized patients with a microbiological confirmation of influenza in a third-level university hospital over 10 seasons, from 2009 to 2019. Nosocomial influenza was defined as that infection whose symptoms began 72 h after hospital admission, and its incidence, characteristics and consequences were further analyzed.Results: A total of 1260 hospitalized patients with a microbiological diagnosis of influenza were included, which 110 (8.7%) were nosocomial. Patients with hospital-acquired influenza were younger (71.74 & PLUSMN; 16.03 years, P = 0.044), had a longer hospital stay (24.25 & PLUSMN; 20.25 days, P < 0.001), had more frequently a history of chronic pulmonary pathologies (P = 0.010), immunodeficiency (P < 0.001), and were associated with greater development of bacterial superinfection (P < 0.001), respiratory distress (P = 0.003), and admission to the intensive care unit (ICU) (P < 0.001). In the multivariate logistic regression analysis, the following characteristics were identified as independent risk factors: immunodeficiency (ORa= 2.33; 95% CI: 1.47-3.60); ICU admission (ORa = 4.29; 95% CI: 2.23-10.91); bacterial superinfection (ORa = 1.64; 95% CI: 1.06-2.53) and respiratory distress (ORa = 3.88; 95% CI: 1.23-12.23).Conclusions: Nosocomial influenza is more common in patients with a history of immunodeficiency. In addition, patients with hospital-acquired influenza had an increased risk of bacterial superinfection, admission to the ICU, and development of respiratory distress.& COPY; 2021 Sociedad Espanola de Enfermedades Infecciosas y Microbiologi & PRIME;a Cli & PRIME;nica. Published by Elsevier Espana, S.L.U. All rights reserved.