Q&A

Neuraminidase inhibitors slightly beneficial for shortening flu symptoms

J Fam Pract. 2003 October;52(10):747-769
By
Grant T. Phillips, MD
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  • BACKGROUND: Influenza epidemics cause considerable morbidity and mortality, and account for substantial time lost from work. In general, the elderly and the very young are at greatest risk from serious complications of the flu. Treatment of relatively healthy populations is usually aimed at symptom alleviation and return to work and normal activities.
  • POPULATION STUDIED: The patients in the 24 studies included in this meta-analysis represent a heterogenous population, and results would be applicable to the patient profile of the typical family practice.
  • STUDY DESIGN AND VALIDITY: The authors selected 17 treatment studies and 7 prevention studies using strict criteria. For inclusion, the study had to be a double-blind, randomized controlled trial in English, studying treatment or prevention of naturally occurring influenza with zanamivir or oseltamivir at standard dosing.
  • OUTCOMES MEASURED: The primary outcomes were subjective time to alleviation of symptoms and complications requiring antibiotics. Other outcomes were self-reported return to normal activity or admission to the hospital. Cost-effectiveness was not directly analyzed.
  • RESULTS: Zanamivir reduced symptom duration by an average 0.8 days in healthy individuals (95% confidence interval [CI], 0.26–1.31), 0.9 days (95% CI, 0.05–1.9) in high-risk individuals, and 1.0 days in children (95% CI, 0.48–1.52). Oseltamivir reduced symptom duration by 0.8 days (95% CI, 0.3–1.4 days) in healthy individuals and 0.9 days (95% CI, 0.25–1.5 days) in children, but was not shown to decrease symptom duration in high-risk individuals.
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PRACTICE RECOMMENDATIONS

Oseltamivir (Tamiflu) and zanamivir (Relenza) are effective for reducing the duration of symptoms of influenza by about 1 day when given to healthy individuals aged <65 years, and if given early in the course of the disease. Benefit to individuals aged >65 years and those with chronic medical conditions were not established.

Important outcomes, such as prevention of death and hospitalization due to influenza, were not discussed. No head-to-head trials were included, and these drugs could be considered interchangeable. Patients in the studies had laboratory confirmation of influenza, something that is not always done in general practice.

Given that these drugs are expensive (about $60 for a typical course), routine use for all flu patients may not be cost-effective. Rather, balancing the cost of treatment against risks and benefits need to be individualized. Use of these drugs should not replace primary prevention strategies.

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