GUARDIAN: “You report on a new study in Germany which finds that half the nation’s doctors prescribe placebos (Mind-altering? Report endorses German GPs’ use of placebos, 7 March). But the article risks causing confusion. It’s wrong to say that, “Used to treat depression, placebos have the same effect as antidepressants in about a third of cases.”
Placebo is used in medicine in two quite distinct ways. The first, the one we are all familiar with, is the “sugar” pill given by doctors to patients to instil hope. These keep them happy while time and nature get on with healing. As reported, it is “a question of trust”. How long will that trust last if the doctor routinely deceives his patients? Realistic information, honest advice and genuine encouragement are surely better.
Believing that “something is being done” does, however, obviously raise the spirits. It raises them in patients but just as much in doctors. We are both more likely to interpret the random variations in symptoms that occur in all illnesses as improvement if we have a strong faith in the medicine. Placebos are used in drug trials to equalise this effect.
Random controlled double-blind trials are our most powerful tool in proving whether or not a new drug works. In these, neither the doctor nor the patient knows who is getting the active chemical. The placebo (the “control” medicine) is there to reduce any bias from faith in the treatment. It is not there to influence the symptoms. This is the second meaning of placebo – a neutral dummy pill.
When your article says “placebos had helped 59% of patients who had been suffering from an upset stomach”, it tells us precisely nothing. Compared to what? Virtually all stomach upsets get better over time.
When researchers write, for example, that 20% of the placebo group recovered in a trial and 60% of the active treatment group did, they are not saying that placebos “have the same effect” in a third as many of the patients. They mean that (for the patients with this condition) 20% will recover in the natural course of events, but with the added treatment 60% will recover. It is this added 40% that matters. The placebo has had no effect on recovery.
Most people with depression recover (thank heavens), and many recover without treatment. Many more, however, recover, and much quicker, with antidepressants. Your article states: “The efficacy of a placebo depends on many factors … including the size and colour of a pill.” But the “placebo effect” from a brightly coloured pill is frankly minimal. Depression is a serious disorder which doesn’t just evaporate with sugar pills. The placebo effect referred to in drug trials is just shorthand for that proportion of patients who recover naturally over time.
We must keep distinct these two uses (the inert dummy pill with an explicit scientific function versus the time-honoured but ultimately ineffective distraction) if we are to understand medical trials.”
Via The Guardian
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