Uncertainty in Medicine: A Talk With Dr. Djulbegovic

Uncertainty in Medicine: A Talk With Dr. Djulbegovic

In part 2 of this interview, Benjamin Djulbegovic, MD,
PhD, discusses the uncertainty principle in clinical trials.  Dr. Djulbegovic is associate
professor of medicine, Divisions of Blood and Marrow Transplantation, H. Lee
Moffitt Cancer Center and Research Institute at the University of South
Florida, Tampa.

Oncology News International: What are the ethical implications of the uncertainty principle?

Dr. Djulbegovic: An ethical issue arises in the assessment of the quality of
the preexisting knowledge. In recent years, increasing evidence points to
systematic review and meta-analysis, when possible, as the best method for
research synthesis of available knowledge regarding a given treatment. The
logical question then becomes: Is it ethical to perform a trial if it is not
preceded by systematic review and meta-analysis?

A second question relates to the choice of the control group. We should bear
in mind that any testing of medical treatments is an exercise in comparison.
Basing trials on the uncertainty principle addresses this important issue in
the design of a clinical trial—the choice of an adequate comparator for the
intervention under investigation.

Studies violate the uncertainty principle when the intervention and the
control or comparison group are known in advance to be nonequivalent in their
effects on the outcomes of main interest. Even if a study is properly reported,
extra caution might be needed in its interpretation if the choice of the
comparator treatment was not based on uncertainty about the relative value of
the treatments being assessed.

The main point here is that explicit acknowledgment of uncertainty prior to
the trial is the only mechanism that we have to ensure a proper choice of an
adequate control group. Studies can meet all other quality criteria regarding
conduct and design and can still be biased if the control group was inferior or

For example, we recently found that for every single quality criterion
analyzed, industry-sponsored studies are equal to or better than publicly
sponsored studies. Yet, industry-sponsored studies were more biased because
they more often chose an inferior control group in their trials (as evidenced
by increased percentage of placebo/no therapy comparators in the
industry-sponsored studies).


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