42. Chris Carter, Parapsychology, Skepticism and Ideology (Podcast)

[Chris Noble]

Originally Posted by David Bailey

OK - this is more a plea for some facts/explanation - so please treat it seriously.

Why is it that just about every medical trial uses controls? Why can't you just say cancer X has 58% fatality with current best treatment, so lets try new compound Y and determine if we can do better.

Because it is difficult to use exactly comparable cohorts in different trials. The only sure way is to have a control group in every trial. It would be too easy for pharmaceutical companies to choose patients with less severe cancer and claim that their drug resulted in less fatalities. It has very little if anything to do with the placebo effect.

There have been huge rows in the USA particularly because potential AIDS drugs are not just tried on people, they go through double blind trials, so some people don't get treated - again, if the placebo effect is relatively unimportant, why is research on fatal diseases done that way?

The HIV denialists argue the opposite - that only the AZT trials in the 80s had a straight placebo control group. Subsequent studies have compared AZT vs other antiretrovirals or 1 ARV vs 2 ARVs or 2 ARVS ve 3 ARVs. The results of the first AZT trials were clear there were much more deaths in the placebo arm than in the treatment arm. The placebo was not very good.

Again the reason for the placebo arm is not because researchers expect or observe a significant placebo effect.

Do you have some actual numbers or references?

If you are going to argue that placebos can have a significant effect on objective measures such as survival then perhaps you are the one who should come up with numbers and references. I am not going to get tricked into bearing the burden of proof on that one.

[Interesting Ian]

Originally Posted by Chris Noble

If you are going to argue that placebos can have a significant effect on objective measures such as survival then perhaps you are the one who should come up with numbers and references. I am not going to get tricked into bearing the burden of proof on that one.

The burden of proof is on the person making the assertion. You stated:

"The placebo effect is almost completely limited to subjective measures. As soon as you start looking at objective measures like survival the placebo effect shrinks to barely significant or disappears completely".


First of all I have no idea whether this is true or not. But am I just supposed to believe it without any attempt at any justification on your part?

[David Bailey]

Originally Posted by Chris Noble

If you are going to argue that placebos can have a significant effect on objective measures such as survival then perhaps you are the one who should come up with numbers and references. I am not going to get tricked into bearing the burden of proof on that one.

Well, I have no background in medical matters, but what you are reporting is certainly not what I have read - perhaps you work in the area, so you should have references aplenty.

Certainly if you GOOGLE placabo+cancer you could be forgiven for reaching a different conclusion.

David

[Chris Noble]

Originally Posted by Interesting Ian

The burden of proof is on the person making the assertion.

And David isn't asserting anything? Give me a break. I'm not going to fall for silly tricks.

[Chris Noble]

Originally Posted by David Bailey

Well, I have no background in medical matters, but what you are reporting is certainly not what I have read - perhaps you work in the area, so you should have references aplenty.

Certainly if you GOOGLE placabo+cancer you could be forgiven for reaching a different conclusion.

David

Sure you can google 911+thermite too if you want.

If you can come up with any serious research showing that the placebo effect by itself has a significant effect on objective measures like survival then I'll debate this with you further.

[Interesting Ian]

Originally Posted by Chris Noble

And David isn't asserting anything? Give me a break. I'm not going to fall for silly tricks.

I'm not interested in what David was asserting. But you've answered my question anyway -- namely that you're unable to justify your assertion. I suspected this, but I thought I'd make sure and ask you.

[Chris Noble]

Originally Posted by Interesting Ian

I'm not interested in what David was asserting.

I'm not interested in playing silly games with you.

[Chris Noble]

Originally Posted by David Bailey

Well, I have no background in medical matters, but what you are reporting is certainly not what I have read - perhaps you work in the area, so you should have references aplenty.

I'll be kind and give you a review.


Hrobjartsson, Asbjorb; Gotzsche, Peter C. Is the Placebo Powerless? An Analysis of Clinical Trials Comparing Placebo With no Treatment.
Obstetrical & Gynecological Survey. 56(10):628-629, October 2001.

Placebos allegedly improve subjective and objective outcomes in as many as 30% to 40% of patients with such diverse disorders as pain, asthma, and hypertension. Physicians writing in leading journals have recommended the clinical use of placebos, although many continue to have misgivings. This systematic review examined clinical trials enrolling patients with a variety of clinical conditions, in which they were randomly assigned to either a placebo or no treatment. Pharmacological, physical (manipulative), and psychological (conversational) placebos all were employed. Typically, lactose tablets were used as a pharmacological placebo. Among 114 trials with relevant outcome data were 32 involving binary outcomes in nearly 3800 patients; and 82 involving continuous outcomes that involved 4730 patients.

In trials with binary outcomes, placebo had no significant effect compared with the no-treatment condition. For those with continuous outcomes a beneficial effect of placebo was evident, but only for trials with subjective, not objective outcomes. For both types of trial there was significant heterogeneity among trials. When continuous-outcome trials were analyzed separately for patients with pain, obesity, asthma, hypertension, insomnia, and anxiety, only those dealing with pain exhibited a significant placebo effect. Sensitivity analyses revealed no significant differences among different types of placebo for trials with either binary or continuous outcomes.

This literature review gives little evidence that placebos, in general, have strong clinical effects on either subjective or objective trial outcomes. The investigators believe that using a placebo outside the context of a properly designed and controlled clinical trial cannot be recommended.

Over to you.

[David Bailey]

Chris,

I rather hope that Topher will have something decisive to say on this. I am tempted to offer you

Books & Recordings - Streaming Audio

The point is that you seem to be saying that the commonly held view that the placebo effect is important in most aspects of medicine is false. That is quite a remarkable claim!

Just from GOOGLEing, there certainly seems to be a range of views on this, for example:

Study evaluates placebo effectiveness

I have a horrible feeling that this is another area where you have two sets of researchers that come to opposite conclusions and scoff at each other

Contrary to you, I don't really see this as a contest. I would genuinely like to know the truth without being fobbed off with some mixture of wishful thinking and distortion (from either side) - and no, that is not a criticism of your quote, purely a general observation.

David

[Chris Noble]

Originally Posted by David Bailey

Chris,

I rather hope that Topher will have something decisive to say on this. I am tempted to offer you

Books & Recordings - Streaming Audio

The point is that you seem to be saying that the commonly held view that the placebo effect is important in most aspects of medicine is false. That is quite a remarkable claim!

No. I'm saying that the placebo effect is smaller than some people like to claim and that it is almost completely limited to subjective measures such as patients self-reported pain.

Just from GOOGLEing, there certainly seems to be a range of views on this, for example:

Study evaluates placebo effectiveness

The study does not contradict anything I have said.

Sham device v inert pill: randomised controlled trial of two placebo treatments

I have a horrible feeling that this is another area where you have two sets of researchers that come to opposite conclusions and scoff at each other

Before you get angry try looking at the research.

Contrary to you, I don't really see this as a contest. I would genuinely like to know the truth without being fobbed off with some mixture of wishful thinking and distortion (from either side) - and no, that is not a criticism of your quote, purely a general observation.

Who says that I am not interested in the truth? You've made a number of assertions about the placebo effect. All I am saying is that the placebo effect is not as strong as some people claim and is largely if not totally restricted to subjective measurements. There are some experiments that do generate a significant placebo effect such as the experiments I mentioned in another thread where patients reported a greater reduction in pain from an expensive placebo compared to a cheap placebo.

Yes we get people to report a reduction in pain with placebos but we are not going to cure cancer.