open label trial is a research
study involving medication, the identity of which is known
to the patient.
In most well-designed clinical
studies, the patient does not know which of two (or more)
alternative treatments he or she is receiving. The purpose
of this secrecy is to keep patient biases from inadvertently
affecting the results. For example, subjects who think that
they are receiving a promising experimental drug may receive
some psychological benefit from this knowledge and actually
appear to improve -- even if the drug itself is not effective
(see also Placebo Effect).
Except in very rare cases, a well-designed
study will avoid open-label trials and instead keep the patients
"blind" with respect to which treatment they are receiving.
The most preferred design is a double-blind
procedure in which neither the patients nor the researchers
know which patients have been assigned to which treatments,
thus avoiding any inadvertent biases on the part of either
patients or researchers.
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain