Intended for healthcare professionals


Oseltamivir: the real world data

BMJ 2014; 348 doi: (Published 09 April 2014) Cite this as: BMJ 2014;348:g2371
  1. Nick Freemantle, professor of clinical epidemiology and biostatistics1,
  2. L J Shallcross, clinical lecturer public health medicine2,
  3. D Kyte, doctoral researcher34,
  4. T Rader, knowledge translation specialist5,
  5. M J Calvert, professor of outcomes methodology4
  1. 1Research Department of Primary Care and Population Health, PRIMENT Clinical Trials Unit, UCL Medical School (Royal Free Campus), London NW3 2PF, UK
  2. 2Research Department of Infection and Population Health, UCL Medical School
  3. 3School of Sport, Exercise and Rehabilitation, University of Birmingham, Birmingham, UK
  4. 4Primary Care Clinical Sciences, University of Birmingham
  5. 5Cochrane Musculoskeletal Group, Centre for Global Health, University of Ottawa, Ottawa, Canada
  1. Correspondence to N Freemantle nicholas.freemantle{at}

To coincide with the publication of an updated systematic review by the Cochrane group the BMJ invited Nick Freemantle and colleagues to consider the current status of observational studies of oseltamivir and their influence on policy and practice

Oseltamivir has become a mainstay in the treatment of influenza, although there is no evidence from clinical trials that it reduces mortality.1 In 2009 we published a review of observational studies examining the effects of oseltamivir in influenza. It was based on a list of studies provided by Roche, the manufacturer, that it claimed provided evidence of the drug’s “real life” value.2 The evidence supported a role for oseltamivir in reducing pneumonia and other complications of influenza in otherwise healthy adults. But we found no evidence that it was associated with mortality, little information on safety, and none on pregnancy related outcomes. We have now updated our evidence by doing a systematic search of published observational studies. Here we explain the advantages and drawbacks of observational data and what they tell us about oseltamivir.

Worldwide influenza is a major public health concern. During an epidemic about 5-15% of the global population develop an upper respiratory tract infection, 3 to 5 million people contract severe disease, and there are between 250 000 and 500 000 influenza related deaths.3 Vaccination is the leading public health control measure to prevent disease and reduce the effect of epidemics, but neuraminidase inhibitors (oseltamivir or zanamivir) or M2 ion channel blockers (amantadine or rimatidine) may be prescribed to reduce the duration of symptoms and improve clinical outcomes. The use of neuraminidase inhibitors increased substantially during the 2009 pandemic of influenza A/H1N1, partly because there was no effective vaccine but also because of concerns over increasing drug resistance to amantadine and rimatidine.3

Why randomised trials aren’t the be all and end all

Randomised controlled trials are the …

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