What is a placebo?

A placebo is designed to look like a treatment but it contains no active ingredient. Some patients in a trial may receive the active drug and others the placebo. Patients receiving the placebo are said to be in the control group. A trial with a control group is called a controlled trial. Ideally, neither the patient nor the doctor directly involved knows which each patient is receiving. As an example, our maternity unit at Whipps Cross Hospital has joined a multicentre study to evaluate the potential benefit of an antibiotic drug to see whether this will reduce the risks of premature delivery in a group of women believed to be at high risk. This trial will be double-blind as neither the patients nor those directly involved in their care will know whether an individual participant is taking the antibiotic or the placebo. The allocation of the tablets follows a strict protocol with the hospital pharmacist supervising the allocation of pre-prepared packets of the tablets. The protocols required have been prepared with the advice of statisticians to ensure that the results can be analysed to determine whether any perceived benefits of medication are real and not due to chance. This trial was completed and unfortunately the antibiotics did not result in any improvement over the controls.

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