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3 comments:
I think it's really impressive that the this consensus document has been published so quickly, and that there is so much cooperation among the ID groups that such a consensus can be possible in such a short span of time. And it reflects well on the community.
But I want to throw a bit of spanner in the works and suggest that it represents more than a bit of pseudoscience. (Must be a bit of a contrarian, lah!!)
What's my basis for saying so?
Well, the group starts of by saying : "The aim of this paper is to provide evidence-based
consensus recommendations in the areas of infection control, antiviral treatment, chemoprophylaxis, antibiotic stockpiling and vaccination that are applicable for the current pandemic, and also potentially for future epidemics caused by respiratory viruses of differing virulence and transmissibility."
Sounds fantastic.... but truth of the matter is that there is really very little in terms of real evidence to make the claim that recommendations are evidence-based.
This is a relatively new virus, whose biology is still being investigated. It is far from clear that we can use previous viral behaviour to anticipate this particular strain. It is far more infective (supposedly) compared to previous influenza strains. It prefers younger patients, and it is possible that older people who have immunity to previous strains may exhibit some immunity to this novel H1N1. Can we therefore use assumptions based on previous 'pandemic' or 'non-pandemic' influenza? And still claim to be evidence-based?
And yes, the virus appears to be sensitive to antivirals, as compared to other currently circulating strains in the US. This itself questions the assumptions of potential risks of fatalities associated with the current strain. On the other hand, in vitro sensitivity to a drug doesn't mean clinical efficacies so the current expectation of clinical efficacies are pretty much based on assumptions (reasonable though they may sound) rather than any real evidence from clinical trials. Evidence based?
Lastly there is too much dependence on the guru which is the US CDC. The models used and assumptions are pretty much US CDC obtained. Is this valid? The CDC's way of computing case-fatalities through the use of excess mortalities has been questioned (Read Doshi P. Am J Public Health. 2008;98:939–945), as they tend to over overestimate the case-fatalities.
Futhermore, the epidemiology of influenza here (even though we have 2 spikes a year) really do not mimic the very strong seasonal waves seen in temperate countries experiencing severe temp drops during winter.
This is a pandemic that has caught many people on the wrong foot. We should be honest about the fact that we understand too little about this virus at the moment. We can make reasonable (though clearly challengeable) assumptions based on our understanding of past influenza infections...... But the world is really quite different now, and there are drugs available now that we did not have in the past, so it may be too early to claim that these recommendations are 'evidence-based'.
Well, it wouldn't be right if I didn't disagree with you now, would it, gig? :)
Certainly it is a new virus and facts are still coming in, and whatever evidence we have at hand may be obsolete in a week's time. But that doesn't mean that the understanding isn't based on evidence. There are grades of evidence, and this is the best we have now. The alternative would be to not look at facts and evidence at all?
As for the seasonal patterm of influenza here, I suspect you know better than I do. All I have to say is that we probably under-diagnose seasonal flu, and are not too discriminating when it comes to attributing deaths due to it - elderly patients who die of pneumonia in hospitals rarely receive a diagnosis of influenza.
What interests me also is how the climate affects the spread of this flu virus, but that kind of research will have to wait until more urgent work is done.
Well, you know that the objective of EBM is to objectively evaluate the evidence for making therapeutic claims or in the formulation therapeutic guidelines etc. If not direct evidence exists, or if assumptions are made from indirect evidence, these should be made clear. As should the limits of the assumptions.
The consensus guidelines presents it all as if the data is quite clear and undisputed.... that assumptions are proven facts.
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