Placebo = the illusion of a cure

The following short passage originates from the abstract of an article that I published in 1998; it is entitled TOWARDS A RISK BENEFIT EVALUATION OF PLACEBOS: the benefits of placebos are often not clearly defined. Generally speaking, the potential for benefit is considerable. The risks are similarly ill defined. Both direct and indirect risks are conceivable. On balance, the risk-benefit relation for placebo could be favourable. Under certain conditions, the clinical use of placebos might therefore be a realistic option. In the final analysis, however, our knowledge for a conclusive risk-benefit evaluation of placebo is incomplete.

Today, I would phrase my conclusion differently: the benefits of placebo therapy are uncertain, while its risks can be considerable. Therefore the use of placebos in clinical routine is rarely justified.

What brought about this change in my attitude?

Lots of things, is the answer; 18 years are a long time in research, and today we know much more about placebo. In my field of inquiry, alternative medicine, we know for instance that, because the mechanisms by which placebos operate are now better understood, some alt med enthusiasts are claiming that placebo effects are real and therefore justify the use of all sorts of placebo treatments, from homeopathy to faith healing. They say that these ineffective (i.e. no better than placebo) therapies are not really ineffective because they help many patients via the well-documented placebo response.

If you are of this opinion, please read the excellent article David Gorski recently published on this issue. Here I want to re-visit my question from above: WHAT DO WE KNOW ABOUT THE RISKS BENEFIT BALANCE OF PLACEBO?

The benefits of placebo can seem impressive on first glance: after receiving placebos, patients can feel better, have less symptoms, need less medication and improve their quality of life. Who would be against any of these outcomes, particularly considering that placebos are usually inexpensive and readily available everywhere?

However, before we get too enthusiastic about the benefits of placebos, we need to consider that they are unreliable. Nobody can predict who will respond to placebo and who won’t. Despite intensive research, it has not been possible to identify placebo-responders as a distinct group of individuals from non-responders. The usefulness of placebos in clinical routine is therefore quite limited. Furthermore, placebo effects are normally only of short duration. Therefore they are not suited for any long-term therapy.

Crucially, placebos almost never effect a cure. They may improve subjective symptoms, but they do not normally cure the disease or remove its causes. A placebo therapy will reduce pain, for instance, and thus it can ease the suffering. If a back pain is caused by a tumour, however, a placebo will not diminish its size or improve the prognosis.

The notion that placebos might cause harm seems paradoxical at first glance. A placebo pill contains no active ingredient – how can it then be harmful? As I have stressed so often before, ANY INEFFECTIVE TREATMENT BECOMES LIFE-THREATENING, IF IT IS USED AS A REPLACEMENT FOR AN EFFECTIVE THERAPY OF A SERIOUS DISEASE. And this warning also applies to placebos, of course.

Seen from this perspective, the much-praised symptomatic relief brought about by a placebo therapy can become a very mixed blessing indeed.

Let’s take the above example of the patient who has back pain. He receives a placebo and subsequently his agony becomes more bearable. Because this approach seems to work, he sticks with it for several month. Eventually the analgesic effect of the placebo wears off and the pain gets too strong to bear. Our patient finally consults a responsible doctor who diagnoses a bone cancer as the cause of his pain. The oncologist who is subsequently consulted regrets that the patient’s prolonged placebo therapy has seriously diminished his chances to cure the cancer.

This may look like an extreme example, but I don’t think it is. Exchange the term ‘placebo’ with almost any alternative treatment, or replace ‘back pain’ and ‘cancer’ with virtually any other conditions, and you will see that such events cannot be rare.

In most instances, placebos may seem helpful but, in fact, they offer little more than the illusion of a cure. They very rarely alter the natural history of a disease and usually achieve little more than a slight, short-term improvement of symptoms. In any case, they are an almost inevitable companion to any well-administered effective treatment. Prescribing pure placebos in clinical routine is therefore not responsible; in most instances, it amounts to fraud.