Intended for healthcare professionals


Stockpiling oseltamivir: Roche clarifies data for improved mortality with oseltamivir

BMJ 2005; 331 doi: (Published 17 November 2005) Cite this as: BMJ 2005;331:1203

Re: Tamiflu: NNT to prevent a pandemic flu death may be a million

Recent discussions in his journals relating to the stockpiling of
oseltamivir for pandemic influenza have focussed on number needed to treat
(NNT) to avert one fatal case of influenza (1,2). Notwithstanding the
relevance of this parameter, from an economic point of view NNT to avert
one hospitalisation should also be considered. Severe influenza-related
disease leading to hospitalisations has various economic impacts within an
already disruptive society suffering from pandemic influenza. In
particular, hospitalisations will further strain an already overburdened
health-care system during pandemic situations and severe disease involves
production losses in various economic sectors, inclusive crucial civil
services and the health-care system itself.

Whereas NNT to avert one death may be 1800-3200 (3,4) depending on
the exact assumptions, pooled clinical trials (5) show that NNT to avert
one hospitalisation are 97 (all-cause mortality) or 142 (more stringent
influenza-related mortality only). These NNTs for hospitalisations were
derived from pooling 10 randomised clinical trials among patients
presenting to the GP within 36 hours of first ILI-symptom onset (also
influenza infection was confirmed afterwards). As indicated previously
(1), such NNTs probably result in cost savings for oseltamivir treatment
of persons presenting with influenza-like illness at the GP’s office. Next
to these potential cost savings, reductions in hospitalisations and severe
diseases may be crucial in pandemic situations to alleviate the already
overburdened health-care system and avert further breakdown of vital civil
services due to large-scale sickness absence. In particular, it can easily
be derived from the pooled trials that potentially the number of
hospitalisations can be reduced by more than 50% through large-scale
oseltamivir treatment.

Furthermore, we note that additionally indirect effects of
oseltamivir treatment during pandemic situations may occur. In particular,
the probability that an infected person will transmit influenza to others
may be reduced by as much as 80% through antiviral treatment (6).
Consequently, instead of causing 2 new infections on average in a
susceptible population (the so-called R0), less than 1 new infection will
only be caused by an influenza-infected person on oseltamivir treatment.
Next to the direct effect of oseltamivir on hospitalisations outlined
above, also this indirect effect on transmission may prove to be of
crucial importance during an influenza pandemic.

1. Grove ML. NNT for oseltamivir. November 24th

2. Rouse A. Tamiflu: NNT to prevent a pandemic flu death may be a million. November 28th

3. Thompson WW, Shay DK, Weintraub E, Brammer L, Cox N, Anderson LJ,
Fukuda K. Mortality Associated With Influenza and Respiratory Syncytial
Virus in the United States. J Am Med Assoc 2003;289:179-86

4. Nordstrom et al at

5. Kaiser L, Wat C, Mills T, Mahoney P, Ward P, Hayden F. Impact of
Oseltamivir Treatment on Influenza-Related Lower Respiratory Tract
Complications and Hospitalizations. Arch Intern Med 2003;163:1667-72

6. Longini IM, Halloran ME, Nizam A, Yang Y. Containing Pandemic Influenza
with Antiviral Agents. Am J Epidemiol 2004;159:623-33

Competing interests:
Dr MJ Postma received research grants from Roche to study the pharmacoeconomics of oseltamivir

Competing interests: No competing interests

07 December 2005
Maarten J Postma
Associate Professor
University of Groningen (Netherlands)