Angry Doctor

Monday, June 23, 2008

What's wrong with the placebo effect?

Reader sprachen sie singlish, commenting on this previous post, wrote:


Never figured out why the Placebo had such bad rep.


Statistically significant improvement for the patient, no side effects. What more could your ask for when apply the Harm Principal?


What's wrong, indeed, with the placebo effect?

(Or more appropriately, with "placebo effects", since it is an umbrella term that covers a number of mechanisms which might affect a patient's physiology or how he perceives his symptoms.)

It is a commonly posed question and a common defence used by proponents of alternative medicine when evidence shows that their favoured modality of treatment is no better than placebo, and that any beneficial effect observed as a result of that therapy is therefore also likely due to the placebo effect.

Because it is a commonly posed question and a commonly used defence, it is a question that has been answered many times by science and medical writers and bloggers. angry doc does not claim to be able to answer the question comprehensively or in depth, but he will do the best he can, with regards to the study in question.

First of all, the improvement observed in the study is not large enough to be considered clinically significant.

That aside, it is also worth noting that while the parents and clinicians all reported improvement in their scores, scores given by the subjects themselves were a more mixed result - some subjects reported improvement in certain domains but felt they did worse in other domains. In other words, the observers thought that the subjects were functioning better, regardless or whether or not the subjects themselves were feeling better - the placebo effect affects the observers, and not the subjects! This of course has ethical implication when it comes to using a treatment on subjects who cannot communicate how they are feeling - patients such as infants, children, those who are mentally-impaired, and even pets; we can think that we are helping them, when in fact we may be doing nothing, or indeed harm to them.

Also, it is not true that there are no side effects with placebos or biologically non-active agents. Patients given non-active agents can in fact develop adverse effect to them, as was the case with one patient in this study, who had to drop out of the study. This is known as the nocebo effect. Placebos, because we do not always know the precise mechanism by which they work, are often unpredictable in their effect, and can in fact have the reverse effect from that which is desired.

Finally, even if we take the result of this study to mean that placebos are effective for ADHD in children and adolescent, the question of what to give the patients remain: do you give them "a mixture of rice protein powder and a small amount of activated charcoal" or "0.3% hypericin... free of heavy metals, pesticides, and adulterants"? Or something else which has already been proven to be more effective than placebo for ADHD?

If you choose to give a patient a placebo, do you tell him you are giving him a placebo, or do you lie to him and tell him you are giving him "something that works"? Do you want to lie to your patient? Would you want your doctor to lie to you?

The fact is there are practitioners out there who are prescribing treatment to patients which have been shown to be no superior to placebo. If indeed all that they are giving is the placebo effect, then does it justify the cost to the patients? Does it justify the practitioner's time learning all he learnt? Does it not make the whole practice dishonest?


Having said that, all 'healers' use the placebo effect to a degree in his or her practice. The simple ritual of a consultation is sometimes all it takes to make the patient feel better. It is probably impossible to quantify or eliminate such effects from our practice, but angry doc feels that where we know that a treatment is no better than placebo, it is detrimental to the patient-doctor relationship to prescribe it as "something which works", or to not resort to something which has indeed been proven to work.

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10 Comments:

  • Replace "placebo" with "making people feel good", and "doctors" with "social workers", and you have the far more commonly held misconception that what social workers do (and *should* do) is to make people feel good. Similarly flawed though. Thanks for a great post, angrydoc.

    By Blogger cognitivedissonance, At June 23, 2008 11:49 pm  

  • what is the placebo is necessary as in the pt asks for something but you know given time, the condition will go away by itself? so what's wrong with giving placebo then?

    Quote wiki: Steele (1891, pp 277–278)"To argue with a man, and especially with a woman, that there is little the matter with them might be thought injudicious, and to advise them to return at a more convenient occasion requires more time and resolution than writing out a prescription or administering a placebo."

    By Anonymous lh, At June 24, 2008 11:43 am  

  • Thanks for the reply. That was quite insightful. I was particularly drawn to this statement.

    Having said that, all 'healers' use the placebo effect to a degree in his or her practice. The simple ritual of a consultation is sometimes all it takes to make the patient feel better.

    My comments were motivated by my perception that society, particularly its younger members, are getting over medicated. Much of this due to unrealistic expectations or just bad lifestyle choices.

    A quick and dirty pill to fix it is preferred to the difficult task of changing lifestyle. This is where I would see the subtle use of the placebo effect(not an out right sugar pill) could be use to manage expectations or just nudge the patient away from meltdown without medication.

    For example managing the expectations of kiasu Singaporean parents who want to get Ritalin for their naughty but otherwise normal kid so that he can keep up with the other kids in class.(btw are the risks during long term usage at early ages know? Can a GP prescribe Ritalin?)

    Alas, in Singapore the polyclinic system does not seem allow one to build relationships with a doctor as I have rarely meet the same doctor twice.

    By Anonymous Sprachen Sie Singlish?, At June 24, 2008 3:53 pm  

  • Certainly from the point of view of the doctor it may seem expedient to dismiss patients who do not really require a medicine with a placebo, but such a practice can backfire.

    Patients may develop a nocebo effect and return with a complaint of a 'drug allergy', to say maybe vitamin C or calcium tablets, which is embarrassing for all concerned.

    Worse still, if an antibiotic is given as a placebo for a viral infection, the viral rash that often accompanies some infections (the exanthems) can be mistaken for an allergy, which means the patient may be unnecessarily banned from taking a useful antibiotic when he does indeed need it.

    I think if we truly want to change patients' expectations and prevent over-medication, we need to be honest with them and not try ot fob them off with placebo. It may be hard to start, but eventually patients must learn that sometimes the only thing they need from doctors is some good advice.

    (I am not familiar with Ritalin though, so I can't answer your question, SSS.)

    By Blogger angry doc, At June 24, 2008 5:59 pm  

  • I am curious then why would placebos be widely used in clinical trials then? Wouldn't it cause the pt(potential) harm?

    Do the placebos in research setting means the placebo is actually no medicine at all? or they were given something seemingly innocent eg: sugar pill.

    By Anonymous lh, At June 24, 2008 10:10 pm  

  • You will then not be surprised to learn that the ethics of placebo-controlled trials is a subject that is much discussed.

    Indeed we should ask ourselves whether it is ethical to give someone who has a disease something that is not known to be effective for the sake of knowledge, and - what is worse - not let them have a choice to whether they will get the test substance or the placebo.

    I am no moral philosopher or ethicist, but I would say that there is a difference between giving someone a placebo in the context of a trial where there is informed consent (i.e. the subject knows he may be given a placebo), and giving a someone a placebo with the intention of deceiving him into thinking that he is given something that will help him.

    Placebos in drug trials are usually substances known to be inactive, while in surgical trial it can be just a cut in the skin, and with acupuncture it is a trick needle that retracted when applied to the skin, like a stage dagger.

    Where possible scientists prefer to conduct trials with a placebo-control group because if you assume that the placebo effects in the trial and the control group are equal, then any observed difference must be due truly to the active agent and not due to placebo.

    There are of course circumstances where this is not possible, or where the ethical dimension becomes more complicated.

    For example, if we know that hypertension is bad for patients, and we want to see if a drug is effective for reducing blood pressure and preventing strokes and heart attacks, then the 'best' way to do this will be to give one groups of subjects the drug, and the other group a placebo. But obviously this is unethical, and so we give one group the test drug, and the other group a drug known to reduce blood pressure (which becomes an 'active' placebo, as it were), and then we monitor the blood pressure and rates of strokes and heart attacks closely. As soon as one group shows a higher incidence of strokes and/or heart attacks, we end the trial, break the code, and put both groups on the better drug if they wish. If you recall, most trials that made it into newspapers in recent years fall into this category.

    Another controversial area is that of placebo-surgery or sham surgery. Is it ethical to subject someone to the risk of anaesthesia, even with consent?

    (One story that I remember involves a surgeon who was seeing good results with a technique he devised. But even then, he asked himself if his success was really due to his surgery, or if it was just the placebo effect. He recruited a groups of patients and told them he would randomise them into a real surgery or a sham surgery group, with the proviso that if a patient who underwent a sham surgery did not feel better, he would be given the real surgery. As I recall his results became worse, with many patients who had the real surgery believing that they had a sham surgery and asking for the real surgery!)

    Proponents of alternative medicine often claim that placebo-controlled trials are not suitable to test their modality of treatment because it is more 'individualised' and treatment must be 'personalised' and adjusted from visit to visit. Of course that begs the question of how they then know if their results are in fact placebo effects.

    So yes, you are right to observe that placebo-controlled trials have an ethical dimension to them, but at the same time, given what we know about the placebo effect, is probably something we need until something better comes along.

    By Blogger angry doc, At June 24, 2008 11:01 pm  

  • Very good post. I wasn't aware that there there was the "nocebo" effect! :)

    I've read that athletes who think they are given drugs (but in reality only a placebo), also perform better than those who know they are not given drugs!

    By Blogger Quantum Mechanic, At June 25, 2008 9:00 am  

  • tks for elaborating..which adds to the curiosity..

    in the hypertension eg. wouldn't it make more sense if the placebo is *nothing. If the placebo is active, how do they make the deduction that any observed difference is due to the tested drug. how accurate is such trials? I've thought the placebo cannot be active at all..

    if it is a blind test, the pt will not know what they get- so since they give informed consent to take part, the ethical qn of getting the tested drug doesn't matter.

    like the sham surgery eg.- so maybe the 'observeed success' which are not authenticated by the trial are not deemed success? or maybe he just need to redesign his experiment.

    "Of course that begs the question of how they then know if their results are in fact placebo effects."
    correct-but its's also possible you also don't know otherwise right

    By Anonymous lh, At June 25, 2008 5:49 pm  

  • "in the hypertension eg. wouldn't it make more sense if the placebo is *nothing."

    Well, since hypertension is bad for patients, we can't give them nothing at all for the duration of the trial.

    "If the placebo is active, how do they make the deduction that any observed difference is due to the tested drug."

    Yes, in that case it is not truly a placebo, but a "head-to-head" trial. I made up the term 'active placebo' to explain how we test new drugs for conditions for which good treatment already exist.

    In such trials the assumption is that all other things being equal (and they adjust for effects due to age, severity of disease, other illnesses the patient may also have, etc.), the difference in the observed effect is due to the differences in effects of the drugs. While this is a big assumption to make for one person, with a large enough population and long enough time individual differences are believed to even out. This is why we sometimes speak of the 'power' of a study.

    "correct-but its's also possible you also don't know otherwise right"

    Er... that is so confused I don't know where to start.

    By Blogger angry doc, At June 25, 2008 6:15 pm  

  • oh i see..that's informative,tks

    except the last bit-since you are confused, I shall not add to it.

    By Anonymous lh, At June 26, 2008 5:09 pm  

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