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Höschl C. Placebo: scam or a useful tool? Keynote lecture, 22nd WONCA (World Organization of Family Doctors [World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians]) Europe Conference, Praha, 28.6.-1.7.2017

29. 6. 2017

Placebo is a medicament containing no pharmacologically effective substance. Its efficacy is reflected in the brain activity mapped using fMRI. Use of placebo in clinical research is discussed from methodological, ethical and technical perspectives.

First, without placebo-controlled studies the proof of efficacy of a new drug is almost impossible. A direct comparison with placebo is often necessary.

Second, the Helsinki declaration says that benefits, risks, burdens and effectiveness of a new intervention must be tested against already proven intervention. This condition is not met with placebo. This paradox is solved by diminution of the respective wording: The use of placebo, or no treatment, is acceptable in studies where no proven intervention exists or where for methodological reasons its use is necessary.

Third, it is sometimes difficult to ensure blinding the placebo.

Major problem of clinical pharmacology is a significant increase of the placebo effect in recent decades and a fading of a verum - placebo signal. Design of a study, type of institution, patient’s characteristics, rating factors, outcome measure, type of a symptom or a disease, type of medication and dosing schedule, sample size, randomization, cultural context, and qualification of raters may contribute to the observed decrease of the signal.