Placebo-controlled study
Such intentionally inert placebo treatments can take many forms, such as a pill containing only sugar, a surgery where nothing efficacious is actually done (just an incision and sometimes some minor touching or handling of the underlying structures), or a medical device (such as an ultrasound machine) that is not actually turned on.
Also, due to the body's natural healing ability and statistical effects such as regression to the mean, many patients will get better even when given no treatment at all.
"[1]p.195 More broadly, the aim of a clinical trial is to determine what treatments, delivered in what circumstances, to which patients, in what conditions, are the most effective.
[2][3] Therefore, the use of placebos is a standard control component of most clinical trials, which attempt to make some sort of quantitative assessment of the efficacy of medicinal drugs or treatments.
A blind can be imposed on any participant of an experiment, including subjects, researchers, technicians, data analysts, and evaluators.
Unblinding that occurs before the conclusion of a study is a source of experimental error, as the bias that was eliminated by blinding is re-introduced.
The outcomes within each group are observed, and compared with each other, allowing us to measure: It is a matter of interpretation whether the value of P-NH indicates the efficacy of the entire treatment process or the magnitude of the "placebo response".
(Wang et al. provide the example of late-phase diabetes, whose natural history is long enough that even a crossover study lasting one year is acceptable.
[8] This apparent placebo effect may have occurred because: In some cases, a study participant may deduce or otherwise obtain information that has been blinded to them.
[9] In 1747, James Lind (1716–1794), the ship's doctor on HMS Salisbury, conducted the first clinical trial when he investigated the efficacy of citrus fruit in cases of scurvy.
[10] He noted that the pair who had been given the oranges and lemons were so restored to health within six days of treatment that one of them returned to duty, and the other was well enough to attend the rest of the sick.
Even so, this was a significant departure from the (then) customary practice of contrasting the consequences of an active treatment with what Flint described as "the natural history of [an untreated] disease".
This was given regularly, and became well known in my wards as the placeboic remedy for rheumatism.Flint[17]: 21 treated 13 hospital inmates who had rheumatic fever; 11 were "acute", and 2 were "sub-acute".
[17]: 32–34 In the thirteenth case, Flint expressed some doubt whether the particular complications that had emerged (namely, pericarditis, endocarditis, and pneumonia) would have been prevented if that subject had been immediately given the "active treatment".
The 79 non-responders' reports showed that if they were considered as an entirely separate group, there was a significant difference the "success rates" of Drugs A, B, and C: viz., 88%, 67%, and 77%, respectively.
The up-to-that-time practice was to allocate subjects alternately to each group, based on the order in which they presented for treatment.
The Nuremberg Code, which was issued in August 1947, as a consequence of the so-called Doctors' Trial which examined the human experimentation conducted by Nazi doctors during World War II, offers ten principles for legitimate medical research, including informed consent, absence of coercion, and beneficence towards experiment participants.
This does not exclude the use of placebo, or no treatment, in studies where no proven prophylactic, diagnostic or therapeutic method exists.In 2002, World Medical Association issued the following elaborative announcement: Note of clarification on paragraph 29 of the WMA Declaration of HelsinkiThe WMA hereby reaffirms its position that extreme care must be taken in making use of a placebo-controlled trial and that in general this methodology should only be used in the absence of existing proven therapy.
"Talking therapies" (such as hypnotherapy, psychotherapy, counseling, and non-drug psychiatry) are now required to have scientific validation by clinical trial.
