A placebo (
/pləˈsiboʊ/; Latin: I shall please[2]) is a simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient. Sometimes patients given a placebo treatment will have a perceived or actual improvement in a medical condition, a phenomenon commonly called the placebo effect.
In medical research, placebos are given as control treatments and depend on the use of measured deception. Common placebos are inert tablets, sham surgery,[3] and other procedures based on false information.[1] However, placebos can also have a surprisingly positive effect on a patient who knows that the given treatment is without any active drug, as compared with a control group who knowingly did not get a placebo.[4]
In one common placebo procedure, however, a patient is given an inert pill, told that it may improve his/her condition, but not told that it is in fact inert. Such an intervention may cause the patient to believe the treatment will change his/her condition; and this belief may produce a subjective perception of a therapeutic effect, causing the patient to feel their condition has improved — or an actual improvement in their condition. This phenomenon is known as the placebo effect.
Placebos are widely used in medical research and medicine,[5] and the placebo effect is a pervasive phenomenon;[5] in fact, it is part of the response to any active medical intervention.[6] Archie Cochrane suggested in 1972[7] "It is important to distinguish the very respectable, conscious use of placebos. The effect of placebos has been shown by randomised controlled trials to be very large. Their use in the correct place is to be encouraged […]"
The placebo effect points to the importance of perception and the brain's role in physical health. However, when used as treatment in clinical medicine (as opposed to laboratory research), the deception involved in the use of placebos creates tension between the Hippocratic Oath and the honesty of the doctor-patient relationship.[8] The United Kingdom Parliamentary Committee on Science and Technology has stated that: "...prescribing placebos... usually relies on some degree of patient deception" and "prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS."[3]
Since the publication of Henry K. Beecher's The Powerful Placebo [9] in 1955, the phenomenon has been considered to have clinically important effects.[10] This view was notably challenged when, in 2001, a systematic review of clinical trials concluded that there was no evidence of clinically important effects, except perhaps in the treatment of pain and continuous subjective outcomes.[10] The article received a flurry of criticism,[11] but the authors later published a Cochrane review with similar conclusions (updated as of 2010).[12] Most studies have attributed the difference from baseline till the end of the trial to a placebo effect, but the reviewers examined studies which had both placebo and untreated groups in order to distinguish the placebo effect from the natural progression of the disease.[10] However these conclusions have been criticized because of the great variety of diseases—more than 40—in this metastudy. The effect of placebo is very different in different diseases. By pooling quite different diseases the results can be levelled out.
The placebo effect has sometimes been defined as a physiological effect caused by the placebo, but Moerman and Jonas have pointed out that this seems illogical, as a placebo is an inert substance that does not directly cause anything. Instead they introduced the word "meaning response" for the meaning that the brain associates with the placebo, which causes a physiological placebo effect. They propose that the placebo, which may be unethical, could be avoided entirely if doctors comfort and encourage their patients' health.[11] Ernst and Resch also attempted to distinguish between the "true" and "perceived" placebo effect, as they argued that some of the effects attributed to the placebo effect could be due to other factors.[23]
The placebo effect has been controversial throughout history. Notable medical organizations have endorsed it,[24] but in 1903 Richard Cabot concluded that it should be avoided because it is deceptive. Newman[25] points out the "placebo paradox", – it may be unethical to use a placebo, but also unethical "not to use something that heals". He suggests to solve this dilemma by appropriating the meaning response in medicine, that is make use of the placebo effect, as long as the "one administering… is honest, open, and believes in its potential healing power".[8] Another possible resolution of the ethical dilemma might come from the "honest placebo" effect found in a 2010 study[4] carried out by researchers in the Program in Placebo Studies at the Harvard Medical School, where patients with irritable bowel syndrome experienced a significant beneficial effect even though they were told the pills they were taking were placebos, as compared to a control group who received no pills.
/pləˈsiboʊ/; Latin: I shall please[2]) is a simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient. Sometimes patients given a placebo treatment will have a perceived or actual improvement in a medical condition, a phenomenon commonly called the placebo effect.In medical research, placebos are given as control treatments and depend on the use of measured deception. Common placebos are inert tablets, sham surgery,[3] and other procedures based on false information.[1] However, placebos can also have a surprisingly positive effect on a patient who knows that the given treatment is without any active drug, as compared with a control group who knowingly did not get a placebo.[4]
In one common placebo procedure, however, a patient is given an inert pill, told that it may improve his/her condition, but not told that it is in fact inert. Such an intervention may cause the patient to believe the treatment will change his/her condition; and this belief may produce a subjective perception of a therapeutic effect, causing the patient to feel their condition has improved — or an actual improvement in their condition. This phenomenon is known as the placebo effect.
Placebos are widely used in medical research and medicine,[5] and the placebo effect is a pervasive phenomenon;[5] in fact, it is part of the response to any active medical intervention.[6] Archie Cochrane suggested in 1972[7] "It is important to distinguish the very respectable, conscious use of placebos. The effect of placebos has been shown by randomised controlled trials to be very large. Their use in the correct place is to be encouraged […]"
The placebo effect points to the importance of perception and the brain's role in physical health. However, when used as treatment in clinical medicine (as opposed to laboratory research), the deception involved in the use of placebos creates tension between the Hippocratic Oath and the honesty of the doctor-patient relationship.[8] The United Kingdom Parliamentary Committee on Science and Technology has stated that: "...prescribing placebos... usually relies on some degree of patient deception" and "prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS."[3]
Since the publication of Henry K. Beecher's The Powerful Placebo [9] in 1955, the phenomenon has been considered to have clinically important effects.[10] This view was notably challenged when, in 2001, a systematic review of clinical trials concluded that there was no evidence of clinically important effects, except perhaps in the treatment of pain and continuous subjective outcomes.[10] The article received a flurry of criticism,[11] but the authors later published a Cochrane review with similar conclusions (updated as of 2010).[12] Most studies have attributed the difference from baseline till the end of the trial to a placebo effect, but the reviewers examined studies which had both placebo and untreated groups in order to distinguish the placebo effect from the natural progression of the disease.[10] However these conclusions have been criticized because of the great variety of diseases—more than 40—in this metastudy. The effect of placebo is very different in different diseases. By pooling quite different diseases the results can be levelled out.
Definitions, effects, and ethics
A placebo has been defined as "a substance or procedure… that is objectively without specific activity for the condition being treated".[11] Under this definition, a wide variety of things can be placebos and exhibit a placebo effect. Pharmacological substances administered through any means can act as placebos, including pills, creams, inhalants, and injections. Medical devices such as ultrasound can act as placebos.[13][14] Sham surgery,[15][16][17] sham electrodes implanted in the brain,[1] and sham acupuncture, either with sham needles or on fake acupuncture points, have all exhibited placebo effects.[18] Bedding not treated to reduce allergies has been used as a placebo to control for treated bedding.[19] The physician has even been called a placebo;[20]33–34 a study found that patient recovery can be increased by words that suggest the patient “would be better in a few days”, and if the patient is given treatment, that “the treatment would certainly make him better” rather than negative words such as “I am not sure that the treatment I am going to give you will have an effect”.[21] The placebo effect may be a component of pharmacological therapies: Pain killing and anxiety reducing drugs that are infused secretly without an individual’s knowledge are less effective than when a patient knows they are receiving them. Likewise, the effects of stimulation from implanted electrodes in the brains of those with advanced Parkinson's disease are greater when they are aware they are receiving this stimulation.[22] Sometimes administering or prescribing a placebo merges into fake medicine.The placebo effect has sometimes been defined as a physiological effect caused by the placebo, but Moerman and Jonas have pointed out that this seems illogical, as a placebo is an inert substance that does not directly cause anything. Instead they introduced the word "meaning response" for the meaning that the brain associates with the placebo, which causes a physiological placebo effect. They propose that the placebo, which may be unethical, could be avoided entirely if doctors comfort and encourage their patients' health.[11] Ernst and Resch also attempted to distinguish between the "true" and "perceived" placebo effect, as they argued that some of the effects attributed to the placebo effect could be due to other factors.[23]
The placebo effect has been controversial throughout history. Notable medical organizations have endorsed it,[24] but in 1903 Richard Cabot concluded that it should be avoided because it is deceptive. Newman[25] points out the "placebo paradox", – it may be unethical to use a placebo, but also unethical "not to use something that heals". He suggests to solve this dilemma by appropriating the meaning response in medicine, that is make use of the placebo effect, as long as the "one administering… is honest, open, and believes in its potential healing power".[8] Another possible resolution of the ethical dilemma might come from the "honest placebo" effect found in a 2010 study[4] carried out by researchers in the Program in Placebo Studies at the Harvard Medical School, where patients with irritable bowel syndrome experienced a significant beneficial effect even though they were told the pills they were taking were placebos, as compared to a control group who received no pills.
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