You have a serious illness. Your
doctor has tried everything; nothing seems to work, and you’re getting
worse. One day, she suggests you enroll in an experiment, a
clinical trial in which investigators hope to prove that some drug yet
to be approved by the FDA is effective in treating the very illness you
have. You are being offered an opportunity to access a potentially beneficial
treatment that would otherwise be unavailable to you.
But here’s the catch. If you enroll in the study, you
have a fifty-fifty chance of receiving a placebo (a sugar pill), because
the investigators need to have a control group in order to determine for
sure whether the experimental drug is significantly more effective than
a dummy pill. This can only be justified if there are no known alternative
treatments for the given condition, or if the study has already tried all
the alternative treatments and found them to be ineffective. In some studies,
the control in not a placebo but an active drug; such experiments are intended
to compare the efficacy of the experimental drug to that of the known therapy.
In such a study, known as a double-blind, placebo-controlled
clinical trial, neither physician nor patient knows beforehand who is getting
the study drug and who isn’t. Moreover, even if you are randomized to the
study drug, there is no guarantee that the drug will help you; indeed,
it could even make you worse.