Thursday, January 17, 2008

"The silent evidence"-unpublished "negative trials"

Here is a recent WSJ article in which we read about drug trials ( in this instance antidepressants) that do not see the published light of day. WSJ is quoting from a NEJM article a summary of which can be found here.

This is another example of how the solid and valid methods of EBM ( evidence based medicine) can be corrupted and misused to serve a particular end-in this case one that can be discerned by application of the old Mafia rule-follow the money. A number of RCTs are done,which can be done absolutely correctly, but only those trials that support superiority over placebo of the a given drug are submitted for publication. Then, in support of the given drug only the published trials are mentioned.

Note: This is not an indictment of proper application of EBM methods and principles and not an indictment against EBM in general but an indictment against lying and cheating. I only mention the obvious because of what I hope to be a misunderstanding of what I have said from time to time. I have been accused of a paranoid,off the deep end attack against the principles of EBM itself. This was never my intent. Back to the main point-

The lead sentence in the NEJM article nails it- if in a bit understated fashion:

Evidence-based medicine is valuable to the extent that the evidence base is complete and unbiased.

Publication bias is nothing new but perhaps with the impact factor of the NEJM more folks will become aware of the issue and carry a bit more skepticism with them as they attempt to evaluate the efficacy of various medications. Obviously, it is difficult ( more understatement) to evaluate evidence that is unpublished.

The term silent evidence comes from a book I am currently enjoying, entitled "Fooled by Randomness" by a former securities trader named Nassim Taleb. which I have mentioned before. More details and commentary regarding the silent evidence regarding antidepressant trials can be found here at the ever alert blog,Clinical Psychology and Psychiatry:A closer look.

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