On 14-Oct-99 M. Carmen Meerschaert wrote:
> I am quite a novice to the field of clinical research. While reading a
> study which was a double-blind RCT, I noted the conclusion that the
> experimental group did not have a significantly improved response to
> therapy over the placebo group. The conclusion, therefore, was that the
> treatment was ineffective.
>
> My question is this: Are we right to assume that a placebo-treated
> group is a true "control" population when studying a disease which is
> subject to psycho-somatic exacerbations? If this patient population's
> response to placebo is high, might this not be an unfair standard
> against which the treatment modality is measured?
That is a perceptive question.
Part of the answer is that the "placebo" group is a valid control when
the objective is to determine whether the alleged therapeutic content
of the "treatment" (whatever it may be) has an intrinsic additional
effect over and above the effect (if any) of going through the motions
of treatment (as in the "placebo" regime).
On the other hand, it may well be that the "placebo" regime has a
real effect in itself; or it may well be that it does not. The only
way to detemine that is to carry out a trial in which the "control"
group really is untreated in any way, and the "experimental" group
gets the "placebo". Or you could do a 3-way trial with "nothing",
"placebo" and "treatment".
So, if your objective is to determine what sorts of intervention
could have an effect on this disease, you cannot ignore the possibility
that there may be a "placebo effect" (as you point out); and in that
case the placebo-treated group is not a good "control" population for
this purpose.
I hope this helps.
Ted.
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E-Mail: (Ted Harding) <[log in to unmask]>
Date: 14-Oct-99 Time: 09:20:04
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