I have never given a patient an injection of water or saline. "I should hope not" is your probable reaction to this statement, but let me explain.
A 1954 study published in the American Journal of Medicine found that four out of 10 surgical patients suffering severe wound pain reported satisfactory pain relief after an injection of inert saline solution.
This research is one of the many examples of the "placebo effect" documented in the medical literature, and it is not confined to injections. Bread pills have been extensively used as placebos and there have even been examples of placebo surgery.
The word placebo comes from the Latin, meaning "I shall please". The first words of a prayer for the dead are "Placebo Domino - I shall please the Lord". By the early 19th century, it had acquired its modern medical meaning - something "given more to please than benefit the patient".
But the placebo effect is more complex than giving a "sham" treatment to patients. Nor is it just a psychological tonic for the gullible. Henry Beecher, a Harvard medical researcher, found that 35 per cent of patients experience therapeutic benefits from a placebo, regardless of their intelligence.
In an effort to understand the placebo effect, it is useful to make a distinction between illness and disease. Illness is what people feel when they are unwell. Disease assumes the existence of a pathological process.
Many diseases are symptomless. Equally, feeling unwell is not always the result of disease. Placebos may have a powerful effect on the subjective aspects of illness such as pain, discomfort and stress.
Trinity College academics, Petr Skrabanek and James McCormack, in their book Follies and Fallacies in Medicine, make the point that "pills and potions are not a necessary condition of the placebo effect".
That the doctor himself can act as a placebo has been documented in several studies. A Southampton general practitioner identified 200 patients who had symptoms such as headache, backache and tiredness, but in whom he was unable to make a specific diagnosis. He divided them into two groups: one group received a "positive consultation" - they were offered a firm "diagnosis" and strong reassurance that they would speedily recover. The second group were told: "I cannot be certain what is the matter with you, but if you are not better within a few days, please come back".
After two weeks 64 per cent of those who received a positive consultation were better as compared to 39 per cent of those offered uncertainty.
Nor does the complexity of placebos stop there. Doctors themselves can "believe" that their prescribing is having specific effects, even though it has been estimated that 35-45 per cent of modern-day prescriptions are unlikely to make a difference to the disease for which they are prescribed. A classic example is the prescribing of antibiotics for viral illness such as the common cold.
The power of placebos should not be underestimated. They can produce significant side-effects. In trials of aspirin for heart attack patients, the placebo caused nearly as much indigestion as the aspirin.
Placebos can even produce tissue changes in the body. A striking example of this was a 1988 study looking at the use of ultrasound to reduce pain and swelling after wisdom tooth extraction. Patients received either real or dummy ultrasound or no therapy at all.
Amazingly, the dummy ultrasound given by a therapist produced a 35 per cent reduction in facial swelling. This was even higher than the 30 per cent reduction seen in the real ultrasound group. Patients who used the probe themselves did not achieve a significant reduction in swelling, pointing to a role for the belief and bedside manner of the therapist.
Using the placebo effect in a conscious way is now frowned upon by the medical profession. An exception is the teaching of communication skills to maximise the placebo effect of doctors. The Lancet stressed the importance of doctors as human placebos in a 1985 article: "The doctor who fails to have a placebo effect on his patients should be a pathologist. . . In simple English, if the patient does not feel better for your consultation, you are in the wrong game."
Society no longer accepts the idea of doctors "lying" to patients, and so the prescribing of placebos is now considered unethical.
On the other hand, antibiotic prescribing continues to rise, bringing with it problems of side-effects and drug resistance. The cost of futile or ineffective treatments is enormous; clearly, coloured bread would do much less damage than the increasing prescription of stronger "placebos".
But if placebos work, help people and save money, is there a case for bringing back different-coloured dummy pills prescribed in an ethical manner?