May 14, 2010

Explaining limitations of observational studies – in an online video

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Greg Pawelski

May 15, 2010 at 8:41 am

The randomized, controlled clinical trial may likely remain the standard for evidence of clinical decision-making in cancer medicine, however, observational methods and systematic reviews are clearly useful.
Single arm clinical trials provide the tumor response (efficacy) evidence that is the basis for approving new cancer drugs. The vast majority of clinical trials performed are ones that test a new chemotherapeutic regimen against a placebo.
Even with the importance of clinical trials, it is crucial to work on reducing their inherent limitations, including uncertain generalizations, and to expand the use of the randomized clinical trial paradigm to areas beyond proving biological activity, like diagnostic testing.
Evidence based medicine, since the 1970’s, depended upon the randomized, controlled trial. It rests upon the assumption that evidence should be determined and applied as a basis for medical decision-making.
Evidence is based upon quantities, similarities, populations, and averages, rather than qualities, idiosyncracies, individualization, and specifics.
It would be surprising if the most ardent supporter of evidence based medicine would ever advocate a randomized trial for an intervention in which an observational study showed remarkable efficacy in preventing a near death situation.
Many major medical advances have never been subjected to a prospective randomized study before being introduced into routine management because their beneficial effects have been obvious.
Recognizing the reliability of the evidence upon which clinical practice has increasingly come to depend, the time has come for physicians to reassess the value of direct observation, and to trust more readily both the empirical and intuitive discoveries they make each day in their personal experience, even if those discoveries are contradicted by the best available evidence.
There could be nothing more serious than the call for physicians to reconsider what it means to be authentic and true.

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