The ethics of placebo-controlled trials: the case of asthma.

Some have argued that placebo-controlled trials (PCTs) are unnecessary and unethical in conditions such as asthma for which there is standard therapy. This article, by using asthma clinical trials as an example, examines the ethics of PCTs. There remain several scientifically sound reasons to conduct PCTs: (1) ensuring scientific validity of the trial, (2) evaluating new therapies less effective than the gold standard, (3) minimizing the number of patients exposed to potentially inefficacious or dangerous therapy, (4) studying clinical situations in which withdrawal of therapy might be considered, and (5) determining the true incidence of side effects. Opponents of PCTs err by conflating clinical research with clinical practice and ignoring the fact that all clinical research involves some sacrifice on the part of the subject for the ends of the research and the good of future patients. PCTs do not per se violate major ethical codes. Properly conducted, PCTs remain a valuable and ethical tool in the armamentarium of modern scientific medicine.