In determining whether a medical treatment or a pharmaceutical product has a genuine effect, it is important to make a distinction between efficacy and effectiveness. “Evidence Check 2: Homeopathy”, a February 2010 report by the Science and Technology Committee of the UK House of Commons quotes Dr Peter Fisher, Director of the Royal London Homeopathic Hospital:

In simple terms the distinction is between ideal conditions and real world conditions—efficacy being ideal conditions and effectiveness being real world conditions

The same report quotes Professor Edzard Ernst, Director of the Peninsula Medical School, giving this example:

Efficacy tests whether treatment works under ideal conditions; for instance, a hypertensive agent may well be effective under ideal conditions and then will not work in the real world because people experience side-effects.

• A treatment can therefore be either effective or not effective and either efficacious or not efficacious:
• A treatment should be both efficacious and effective.
• If a treatment is not efficacious and not effective, it should obviously not be used.
• If a treatment is efficacious, but not effective, it could still have some use if the effect of the “real world” could somehow be excluded and an ideal situation could be reached or approximated.

A very muddy situation occurs when a treatment is not efficacious, but nevertheless effective. Many alternological treatments fall under this heading. For example, it is well-established that homoeopathy is not efficacious. Yet, it often appears effective. This is rather paradoxical and this type of effectiveness is called the ‘placebo effect’.

A placebo is often called a “sugar pill” since this is its original meaning. It refers to a product or treatment that is known not to have any efficacy to treat a certain condition. Homoeopathic products are a prime example of a placebo.

There are several popular definitions of what a placebo is. For example, this one by psychiatrist Arthur Shapiro [1]:

any therapeutic procedure which has an effect on a patient, symptom, syndrome or disease, but which is objectively without specific activity for the condition being treated

or this one by Dr Howard Brody [2]:

a change in a patient’s illness attributable to the symbolic import of a treatment rather than a specific pharmacologic or physiologic property

In order to test the efficacy of a medical treatment, a group of patients is treated with the treatment, while another group of patients is treated with the non-treatment (placebo). If the treatment group fares better than the placebo group, the new treatment has a genuine chance of becoming an officially accepted treatment.

The placebo effect is not well understood. A certain percentage of people will be cured, even when only treated with a placebo. These people find it often impossible to understand that the treatment did not do anything for them, and will maintain that it cured them.

Confusing correlation with causation, these people often feel that whatever therapy they received, genuinely cured them. This is the way that essentially nonsensical treatments, such as prayers, homoeopathy, magnetism and so many others can remain popular, even when they are known not to work.

• The placebo effect is used to describe a positive effect. If the effect is negative, it is often referred to as the nocebo effect.
• Although there is quite a bit of literature on the subject, the placebo effect is not well understood, but it has been shown that:
• The placebo effect can be powerful, but usually only for minor problems
• The placebo effect is unpredictable. It is not possible to predict who will respond positively to a placebo treatment. A person who reacts strongly today, may not react at all -or even negatively- tomorrow. There is not even a consensus on how many patients experience a placebo effect.
• The placebo effect is culturally specific. Colours can influence the outcome. Red, yellow and orange are associated with a stimulant effect, while blue and green are associated with a tranquillising effect [3]. A bigger pill tends to have a stronger effect than a smaller one. Even the way of administering the placebo has an influence. For example, injected placebos tend to be more effective than oral placebos in migraine treatment.

In the past, medicine was highly paternalistic. The doctor knew what was best for the patient, and if he/she thought that a sugar pill would do the trick, that’s what he/she would prescribe.

However, medicine has evolved. It is no longer considered ethical to deceive patients. Even beyond the ethical, one should question the wisdom of knowingly prescribing non-functional treatments. When the patient finds out about it, he/she will no longer be able to trust doctors and that is potentially far more harmful than the short term gain of prescribing a placebo.

Furthermore, placebo treatments are not necessarily harmless. In the case of serious conditions, they may convince the patient that he/she is getting better, when this is not so. Because of this effect, the patient can be encouraged to postpone or forgo genuine treatment, a decision that can cost her/him her/his life.

Prescribing a placebo is also unnecessary. It is better to prescribe a treatment that actually works, as the placebo effect will automatically complement the genuine effect.

References
[1] A K Shapiro, “Factors contributing to the placebo effect. Their implications for psychotherapy”, American Journal of
Psychotherapy, vol 18 (1964), pp 73–88
[2] Brody H. “Placebos and the Philosophy of Medicine. Clinical, Conceptual and Ethical Issues”, University of Chicago
Press, 1980
[3] A J de Craen, P J Roos, S Leonard de Vrie, J Kleijnen, “Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness”, BMJ,1996 Dec 21–28, vol 313 (7072) pp 1624–6
[4] A J de Craen, J G P Tijssen, J de Gans and J Kleijnen, “Placebo effect in the acute treatment of migraine: subcutaneous placebos are better than oral placebos”, J Neurol, 2000, vol 247: pp 83–188