What can the placebo effect do?

[Mojo]

Another thread here, as well as a discussion on another forum where the placebo effect was held up an an example of "mind over matter" made me wonder about this.

I've seen examples of the placebo effect being cited as a reason for patients feeling better after treatment, or as having caused relief of symptoms such as pain or nausea, which have some subjective component.

Are there any studies which have indicated that the placebo effect can cause changes that can be measured completely objectively, such as (for example) in the levels of particular chemicals in the blood?

 

[blutoski]

Another thread here, as well as a discussion on another forum where the placebo effect was held up an an example of "mind over matter" made me wonder about this.

I've seen examples of the placebo effect being cited as a reason for patients feeling better after treatment, or as having caused relief of symptoms such as pain or nausea, which have some subjective component.

Are there any studies which have indicated that the placebo effect can cause changes that can be measured completely objectively, such as (for example) in the levels of particular chemicals in the blood?

The short answer is: "yes, but..."

There are some conditions whose metrics are objectively measured, and placebo can have positive outcomes.

The 'but' part comes in like this:

1. The statistically significant measureable improvement is not usually medically significant.

2. These conditions usually have some psychological component as well. An example is blood pressure, which is influenced by stress. Another is range of motion, which is an objective measure of pain in a joint. However, it's influenced by the subjective interpretation of pain.


I qualify this by saying that my definition of 'placebo effect' is the difference in outcome between the placebo group and the non-treatment group.

 

[Dave1001]

I qualify this by saying that my definition of 'placebo effect' is the difference in outcome between the placebo group and the non-treatment group.

Good, well-phrased, and rational definition that this thread has lacked.

 

[Jeff Corey]

I don't recall any placebo effects on objectively measurable things being published in scientific journals, but I might be wrong. Mostly it's pain relief or other subjective measures.

 

[blutoski]

Good, well-phrased, and rational definition that this thread has lacked.

Well, in the thread's defense... that was post #2.

I don't recall any placebo effects on objectively measurable things being published in scientific journals, but I might be wrong. Mostly it's pain relief or other subjective measures.

I wish. I'll see if I can find a few citations.

 

[blutoski]

I wish. I'll see if I can find a few citations.

Here: Arch Intern Med. 2000;160:1449-1454: Placebo Lowers Blood Pressure in Nearly One-Third of Patients.

There was no non-treatment group, though, so I'm not sure if we could call this a 'placebo effect' in the sense that I prefer.

 

[Dave1001]

Well, in the thread's defense... that was post #2.



I wish. I'll see if I can find a few citations.

Right you are. Sorry -missed it.

But apparently you didn't consider me the only one, as you found the need to restate it.

 

[Jeff Corey]

Here: Arch Intern Med. 2000;160:1449-1454: Placebo Lowers Blood Pressure in Nearly One-Third of Patients.

There was no non-treatment group, though, so I'm not sure if we could call this a 'placebo effect' in the sense that I prefer.

Sorry, I meant "scientific" in the sense that the study had control groups and that other stuff.

 

[ponderingturtle]

Here: Arch Intern Med. 2000;160:1449-1454: Placebo Lowers Blood Pressure in Nearly One-Third of Patients.

There was no non-treatment group, though, so I'm not sure if we could call this a 'placebo effect' in the sense that I prefer.

This is because a no treatment group would by definition know that they where not getting treatment. I guess you could have a drug group a placebo group that everyone thinks might be getting the drug and a group that gets nothing, but that is not really the issue. We mostly have a fair idea what happens when you don't treat a problem

 

[ponderingturtle]

Sorry, I meant "scientific" in the sense that the study had control groups and that other stuff.

How do you control for a placebo?

 

[Jeff Corey]

How do you control for a placebo?

Easy. One control group gets diddley squat. Nothing. Nada. Bupkis. No treatment whatsoever.

 

[Rasmus]

How do you control for a placebo?

You drug people with whatever you can find in the hospital pharmacy?

 

[blutoski]

How do you control for a placebo?

As Jeff indicated. One group gets the placebo; the other group does not. The difference is the effect of the placebo.

Very few studies have been done to actually test the effect of placebo. Under 130, IIRC.

 

[Mojo]

These conditions usually have some psychological component as well. An example is blood pressure, which is influenced by stress. Another is range of motion, which is an objective measure of pain in a joint. However, it's influenced by the subjective interpretation of pain.

I was wondering if there is anything with no psychological component (or at least with as little as possible). I should have included that in the OP.

The thing is, I've seen all sorts of claims about the placebo effect, ranging from a suggestion that it's some amazing panacea (and we should therefore encourage the use of "alternative" therapies even if they work only via the placebo effect) to the suggestion that the apparent placebo effect is entirely down to the subject's expectations affecting their perception of how they feel, and isn't a "real" effect at all.

 

[ponderingturtle]

As Jeff indicated. One group gets the placebo; the other group does not. The difference is the effect of the placebo.

Very few studies have been done to actually test the effect of placebo. Under 130, IIRC.

I am not suprised, as the point is that a placebo does nothing, you are weighting it agenst something else that does nothing.

 

[Mojo]

I am not suprised, as the point is that a placebo does nothing, you are weighting it agenst something else that does nothing.

The point is that, certainly as far as the patient's perceptions are concerned, a placebo intervention does do something. This is why it is necessary to give the control group in a trial of a therapy a convincing placebo, rather than simply not treating them.

 

[Physiotherapist]

I think that surely the difference is that the non-treatment group are aware that they are not being given any treatment, whereas the placebo group are told that they will be given treatment in some form or another. That has to be the biggest difference. Psychology has to come into this.

I can't remember where now, but I did see something on sham knee surgery that resulted in permanent cure.

 

[asthmatic camel]

I've wondered for some time about the ethics of using placebos in tests, particularly when the patient is seriously, perhaps fatally, ill. Here's a case I chose at random.

I find it most worrying that doctors are willing to prescribe placebos in these circumstances; are there any known cases where a placebo has cured cancer? (No woo sites, please.)

 

[Deetee]

I can't remember where now, but I did see something on sham knee surgery that resulted in permanent cure.

You are probably recalling the Moseley study (which was part of our dear friend Professor Kathy Sykes' UK TV series earlier in the year). This was widely misinterpreted as showing that placebo surgery on the knee "works as well as real surgery".
Also, there was great confusion about the term "surgery", which most people think of as a technique with cutting/ resecting diseased tissues, and reconstructing the healthy remainder. What was actually done was a wash out of the joint with saline solution through a keyhole incision, hardly up there with open heart surgery.

In fact, the study merely confirmed that "surgery" does not work very well for osteoarthritis of the knee (and there is a spontaneous improvement in many people with this condition).

The authors of the study specifically concluded that surgery was "no better than" placebo, in an attempt to help ram home the message that the $millions spent on this type of procedure in the US each year are a complete waste of money.

A lot of alternative therapies employ what I term the "Ineffective Comparator" principle to tout how wonderful they are:e.g:

"Crystal therapy! As good as Dycomycin chemotherapy for leukaemia!"
[Well of course it is as good, since dycomycin trials show it is useless, but the general public go away thinking - "Wow! as good as chemotherapy, huh? Must be great!"]

 

[Badly Shaved Monkey]

"I find it most worrying that doctors are willing to prescribe placebos"

I think it is meant to be unethical in clinical practice, but I am sure there are times when the idea that doing nothing would be better than doing anything else, but the patient needs some help with this. Unlike, the homeopaths, we don't have bottles of pretend medicine readily at hand, so real drugs end up being used. Antiobiotics used for acute viral infections would be an example of such placebo-prescribing with the unfortunate consequence of adding yet further to the unnecessary use of important drugs.