Some words about placebo-controlled trials

The purpose of the placebo-controlled drug trial is to insure that no bias affects the outcome of the drug trial. In general terms, it is important that a patient taking an experimental drug experience an effect that is due solely to the drug, and not the so-called “placebo effect.” The placebo effect can trick the patient into thinking he/she is deriving benefit or harm from a drug when in effect this benefit or harm is actually due to psychosomatic or incidental causes .

Studies of new or even established drugs have much more powerful conclusions when conducted using a placebo arm. These include studies of psychiatric drugs, drugs for heart and lung disease, and even trials in which vitamins are used. In studies where a placebo arm was not used, it is extremely difficult to determine if an outcome was due to equal effectiveness of drug vs no drug, or was the result of a Type II error; i.e., erroneously concluding that there was a difference when, in fact, no difference between drug and no drug existed (or vice-versa).

In conducting a placebo-controlled trial, it is imperative that the participants, doctors, nurses, and patients alike maintain a neutral bias with regard to whether or not a patient is receiving a placebo. It is important, therefore that any discussion about the likelihood of receiving placebo or real drug does not take place during the part of the trial in which the placebo is given. This includes patient-to-doctor, patient-to-nurse, and patient-to-patient conversations. With the recent widespread use of Internet chat rooms and bulletin boards, it is especially important that patients participating in placebo-controlled trials do not discuss details of the trial with others such as whether or not they think they are on a placebo.

Participants in placebo-controlled trials are cautioned in discussing details of their trial before unblinding from placebo, as it may adversely affect the outcome of the approval process by the Food and Drug Administration. In addition, even after unblinding from placebo, a patient discussing details of their trial with another patient that might still be blinded themselves could violate the study protocol. Thus, a drug that would otherwise be promising for use in the treatment of a particular disease might not be approved for use if there is a suspicion that the placebo arm of the trial was violated.

All biomedical research should adopt the standards of the Declaration of Helsinki, a copy of which can be found by clicking on the following link: