Placebo effect drug trials

As mentioned previously in Chapter 1, the placebo effect can create havoc with clinical trials. The first placebo-controlled drug trial was published in 1933. The... 

Swartzman, L. C. 8c Burkell, J. (1998). Expectations and the placebo effect in clinical drug trials why we should not turn a blind eye to unblinding, and other cautionary notes. Clin. Pharmacol. Ther., 64, 1-7. 

Because of the power of the placebo effect, almost anything that is believed in seems to work for some types of medical problems. That is why the late Arthur K. Shapiro described the history of medicine as largely the history of the placebo effect.4 It is also why clinical experience alone cannot tell us whether a particular physical substance is an effective treatment. Placebo-controlled trials are required to demonstrate drug efficacy before drugs are approved for marketing. 

But do the clinical-trial data submitted to the FDA even establish proof of principle Recall that the rather small differences found between drug and placebo in the trials submitted to the FDA could have been due to the breaking of blind on the basis of perceived side effects. It may simply be evidence of an enhanced placebo effect, rather than a true drug effect. As I noted in Chapter i, once side effects are taken into account, the difference between SSRI and placebo is not even statistically significant.30... 

There is yet another possibility. The general assumption is that the effect of a drug adds to the placebo effect, so that the total improvement that patients experience is the drug effect in addition to the placebo effect. This assumption is implicit in the design of placebo-controlled clinical trials, in which the drug effect is assessed as the difference between the response to the drug and the response to the placebo. Anne Harrington, an historian of science at Harvard University and the London School of Economics, calls it the oil-and-water hypothesis. 

Although the tailoring hypothesis does not fit the data, there is another hypothesis that works just fine. It is the idea that antidepressants are active placebos. That is, they are active drugs, complete with chemically induced side effects, but their therapeutic effects are based on the placebo effect rather than their chemical composition. Their small advantage in clinical trials derives from the production of side effects, which leads patients to realize that they have been given the active drug, thereby increasing their expectancy for improvement. 

As in this Japanese study, the placebo effect can also be extremely powerful in drug trials. It is normal for 15 to 20 percent of patients receiving dummy pills in a clinical trial to show varying degrees of improvement. The number can be greater than 35 or... 

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