When drug companies are putting new drugs through clinical trials in
order to seek regulatory approval, they need to compare the efficacy
of the drug to a baseline. This nearly always means the use of a
placebo, defined as "a substance that has no therapeutic effect, used
as a control in testing new drugs."
Often this is simply a sugar
pill, but in studies looking at a physical procedure such as
acupuncture, a sham procedure is carried out. Sham procedures are
also utilised in research experiments to compare novel treatments.
One of the great underlying mysteries about placebos is that they
work, to a certain degree. Patients in placebo groups will get
better, and they will also experience side effects, despite the
absence of any active drug in their systems.
Now a new study published in the
British Medical Journal* has, for the first time, compared
different placebos to determine if there might be differences in the
outcome. The idea being that the ritual associated with
administration might contribute to the effect of the placebo. In the
study, examining patients with repetitive strain injury (RSI),
placebo pills were compared to a sham acupuncture treatment.
The study of 270 individuals with chronic arm pain had two
phases. In the first phase, 135 patients were given sham
acupuncture, and another 135 patients were given a placebo pill for
two weeks. During this period, investigators found no strong
evidence for an enhanced effect with placebo devices compared with
placebo pills.
In the second phase of the study, the same patients were
randomized again, with half the patients entered in a sham
acupuncture device versus real acupuncture trial, and the other half
in a placebo pill vs. real pain pill trial. The acupuncture trial
extended four more weeks (the length believed needed to see
improvement), and the pill trial lasted six more weeks (the length
needed to have the real drug in the bloodstream).
In the second phase of the study, patients receiving sham
acupuncture reported a more significant decrease in pain and symptom
severity than those receiving placebo pills for the duration of the
trials. The results of this study show that the placebo effect
varies by type of placebo used.
The side effects experienced by both placebo groups also showed
up. One in four of the placebo-treated patients, and just under one
in three of the sham acupuncture patients experienced the side effects
listed on the consent forms, which raises interesting questions about
informed consent and side effect reporting in clinical trials.
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