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Oseltamivir Reduces Mortality in Patients Hospitalized with Influenza

By Luciana Borio, M.D., November 15, 2007

In a prospective, cohort study conducted by Allison McGeer and colleagues from the Mount Sinai Hospital in Toronto, Canada, oseltamivir therapy administered to adult patients hospitalized with influenza decreased mortality by almost 80%. The study will be published in the December 15 issue of Clinical Infectious Diseases, currently available online.1

McGeer’s study measured death within 15 days after onset of symptoms among patients with laboratory-confirmed influenza infection who were hospitalized between January 2005 and May 2006. Of 327 adult patients, median age 77 years, 75% had a chronic underlying illness, and approximately 71% had been vaccinated against influenza (vaccination data was available for 303 patients only). Sixteen percent required ICU admission, and 8.3% died within 15 days after onset of symptoms. Approximately 1/3 of patients received antiviral therapy. Patients who were prescribed amantadine were included in the arm that did not receive therapy, as the vast majority of viral isolates during the study period were resistant to amantadine.

Treatment with oseltamivir was associated with a reduction in risk of death by nearly 80% (odds ratio, 0.21; 95% confidence interval 0.06-0.80, P=.03). Antiviral therapy was not associated with a decreased hospital stay. The median length of stay for surviving patients who did not receive oseltamivir therapy was 6 days, and for those who received therapy, it was 8 days.

Conclusion

Previous trials have shown that neuraminidase inhibitor therapy administered to healthy adults up to 48 hours after the onset of symptoms is beneficial in reducing the severity and duration of illness, as well as the risk of complications associated with influenza. 2 In this trial, however, antiviral therapy benefitted older, sicker patients, even when administered after the “48 hour window.” The authors speculate that in healthy adults with influenza, the virus is cleared promptly, obviating the benefit of therapy if given beyond 48 hours of symptom onset. However, in sicker individuals, viral replication might persist beyond the 48 hour window.

This study offers compelling evidence to support the use of antiviral therapy in patients hospitalized with influenza infections. Influenza testing is often done as a result of infection-control surveillance instead of clinical suspicion. Clinicians should maintain a high index of suspicion for influenza during the season as appropriate treatment clearly saves lives.

References

  1. McGeer A, Green KA, Plevneshi A, et al. Antiviral therapy and outcomes of influenza requiring hospitalization in Ontario, Canada. Clinical Infectious Diseases 2007;45:000-000. http://www.journals.uchicago.edu/CID/journal/issues/v45n12/51609/51609.web.pdf

  2. Moscona A. Neuraminidase inhibitors for influenza. N Engl J Med 2005;353:1363-73.