Occurrence of acute otitis and sinusitis in patients hospitalized for influenza.

Introduction: Acute otitis and sinusitis are common complications in patients with influenza and are responsible for increased hospitalization rates. Methods: A five-year retrospective study (2018-2023) was conducted including all patients hospitalized for influenza (etiologic diagnosis by RT-PCR) to identify the incidence and characteristics of cases complicated with otitis and/or sinusitis. Cases associated with other viral co-infections were excluded from the analysis. Results: We identified a cumulative rate of 20.6% (324 cases) of acute otitis (AO) and acute sinusitis (AS) among patients with influenza. Of these, 62.3% had AO, 28.1% AS, and 9.6% concomitant AO and AS. Cases of AO were predominant in the pediatric population (97.0%), while cases of AS were more common in adults (56.1%). Influenza A viruses were identified in 67.2% of patients. The infection with influenza B viruses increased the risk of acute congestive otitis media 2.1-fold (p=0.020), and influenza A viruses increased the risk of acute maxillary sinusitis 2.7-fold (p=0.029). Late presentation to the hospital, with a median of 4 days from the onset of influenza symptoms, was identified as a factor in the occurrence of AO and AS. Conclusions: The risk of AO and AS is increased in patients with influenza, especially in the pediatric population and in late hospital presentations. These findings highlight the importance of proper monitoring and management of patients with influenza to prevent the development of complications, as well as the need to better understand the mechanisms whereby influenza viruses contribute to these secondary conditions.