Patients given the antiviral drug oseltamivir on the day of hospital admission for influenza A had less severe disease and were less likely to die or require intensive care and dialysis or vasopressors (drugs to raise blood pressure) than those who didn't receive early therapy, suggests a US study published last week in Clinical Infectious Diseases.
Researchers in the Investigating Respiratory Viruses in the Acutely Ill (IVY) Network prospectively assessed outcomes among adult flu patients admitted to 24 hospitals in 19 states from October 2022 to July 2023. Roughly half (49%) of the 840 patients received oseltamivir (Tamiflu) on the day of admission, and 51% either didn't receive the drug (14%) or started it later (36%).
"The 2018 Infectious Disease Society of America (IDSA) guidelines for patients hospitalized with suspected or laboratory-confirmed influenza recommend initiation of oseltamivir treatment as soon as possible, regardless of the time since symptom onset," the study authors wrote. "However, ongoing variability in the clinical use and timing of antiviral treatment, along with variation in the influenza virus strains circulating each year, could influence effectiveness."
Lower risk of ICU admission, dialysis, vasopressor use
Relative to patients who didn't receive oseltamivir at admission, those treated early had lower peak pulmonary disease severity (proportional adjusted odds ratio [aOR], 0.60) and a lower risk of intensive care unit (ICU) admission (aOR, 0.25), dialysis or vasopressor use (aOR, 0.40), and in-hospital death (aOR, 0.36).
These findings support current recommendations, such as the IDSA Influenza Clinical Practice Guidelines and CDC guidance, to initiate oseltamivir treatment as soon as possible for adult patients hospitalized with influenza.
Patients treated early, compared with those who received late or no treatment, were also less likely to experience disease progression after the day of hospital admission, per escalation of disease severity on the pulmonary disease ordinal scale by one level (11% vs 21%) or two or more levels (3% vs 7%). Of 14 in-hospital deaths, 4 were in the early-treatment group (1.0% of this group), 7 were in the late-treatment group (2.3%), and 3 were in the no-treatment group (2.4%).
Many hospitalized flu patients receive no or late antiviral treatment, the researchers noted. "Clinicians could be less likely to prescribe antiviral treatment when more than 48 hours have elapsed since a patient’s illness onset," they wrote.
A 48-hour window is often used to identify outpatients who may have a shorter course of illness with antiviral therapy. "However, this 48-hour treatment window does not generalize well to in-hospital settings where some reduction in viral replication—even if not optimal—may be of particular benefit to hospitalized patients who may have prolonged viral replication and higher risk of organ failure and death," the authors wrote, adding that many patients aren't hospitalized for days after symptom onset and may still benefit from an antiviral.
"These findings support current recommendations, such as the IDSA Influenza Clinical Practice Guidelines and CDC guidance, to initiate oseltamivir treatment as soon as possible for adult patients hospitalized with influenza," they concluded.
