Double blind trials / placebo arm

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Double blind trials / placebo arm

Postby CureOrBust » Fri Sep 01, 2006 10:45 pm

Just something that has been bothering me from when i was on rebif.

The CRABS generally have noticeable side effects, and have all been tested in double blind, placebo controlled trials.

How do they ensure that the recipients dont KNOW they are getting the actual CRAB? for example, when I took rebif, i suffered from flu like reactions. Therefore, i think if i was in the placebo arm of a rebif trial, i would pretty quickly know i was injecting saline. Or do they give the placebo arm, something that causes similar side effects to the drug being tested? ie some kind of "poison"?
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Postby sh8un » Fri Sep 01, 2006 11:59 pm

huh...a very good question. I am not sure. When I was participating in research at my hospital (giving Minocycline IV) I was giving placebo which was saline. There is not a whole lot that you could experience with Minocycline other than anaphylactic shock if you are allergic(like any Abx really). I have no idea. I don't think that they can inject you with something that would cause the same side effects. I think, when it is a new drug, and they have no idea what the side effects are, they just tell you that it is experimental and that the following are the possible benefits. They can't probably tell you what to expect as side effect because they would not really know yet. ????????
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Postby CureOrBust » Sat Sep 02, 2006 4:41 am

But when its at the stage of double blind trials, there would of already been a few preceeding less formal trials, and also a fairly big hoo-ha about the drug, and any side effects.

Even if one didnt know anything, if they didnt feel anything at all (assuming no placebo effect...), then you would be more likely to think you are on the palcebo, whereas anyone who suffered side effects such as chills, would be pretty damn sure they are on the actual drug on trial, and therefore, I can't see how it could really be considered a true double blind trial. And if you felt side effects, you would be more susceptable to a placebo benefit.

As for not knowing of possible side effects, I would find it hard to believe that you would be given/injected with anything without being told the possible list of side effects.

I got off my butt and did a search and found the following
Placebo was the same solution as active treatment, without interferon; it consisted of sodium acetate, 0.01 M, with mannitol and human serum albumin

http://www.fda.gov/cder/biologics/review/ifnbser030702r10.pdf
Im no doctor, but the placebo sounds pretty bland.
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Postby sh8un » Sat Sep 02, 2006 9:27 am

That is so briliant. I never though they would do that even though it would make sense for the later phases. WOW...I am glad that you found this. Otherwise I would have started to think that whatever benefit that I thought I was getting from CARBs was from good old miss placebo. Does that sound like a man's name? I guess it would be placeba if it weren't. :o
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Postby CureOrBust » Sat Sep 02, 2006 5:32 pm

Either I am misreading your post, or you misunderstood where I was going.

The placebo they used in the trial appeared to me to be just inert ingredients, that would not cause any side effects. They say "the same solution", but "without interferon". Its the interferon that causes the side effects, and as such the placebo would not have the side effects.

Therefore, those on the placebo arm would know they are on such. Meanwhile, those on the non placebo arm of the study would more likely feel side effects, and therefore be susceptible to a placebo effect.

So i am still wondering (even more now that i found that the palcebo was inert), how you could call it a double blind placebo controlled trial?
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Postby Lyon » Sat Sep 02, 2006 6:33 pm

oo
Last edited by Lyon on Sat May 07, 2011 8:39 am, edited 1 time in total.
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Postby Brainteaser » Sun Sep 03, 2006 1:53 am

Just to complicate/confuse the situation even more, CureO, could it not be that those on the placebo know to expect a reaction (if they were on the real thing) and therefore in their hope of being on the real thing, may actually (falsely) perceive an interferon reaction from the placebo, given particularly that they would not have the experience of knowing what an interferon reaction looks like?
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Postby CureOrBust » Sun Sep 03, 2006 2:14 am

brainteaser, that doesn't confuse it any further, as one purpose of a placebo arm is because one would expect both the placebo and the non placebo arm to have equal effects due to placebo. And as such they always compare the benefit OVER the placebo arm, in the hope that the placebo arm will basically cancel out all placebo effect, in both groups.

The thing that doesn't sit comfortably with me is that the idea of not knowing you are on placebo, is not going to work on medications that have distinct side effects.
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Postby sh8un » Sun Sep 03, 2006 2:19 am

Hi there,
sorry about the confusing post. The reason I said what I did was because I thought that maybe being injected with human protein would still cause a fever or something. I know that it could happen with an IV infusion but that it is rare. I thought if it was injected under the skin or IM it might cause similar reactions. I guess I misread that one. However, since you may or may not have a reaction to albumin and/or the experimental drug, I guess they can get away with saying that you may or may not experience flue like symptoms. Not everyone on interferon has reactions to them.
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Postby Lyon » Mon Sep 04, 2006 5:27 pm

oo
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Postby mrhodes40 » Sat Sep 09, 2006 10:04 am

You're right Cure-o
I posted a thread some time ago called how we get fooled on this topic but this resource http://www.ncbi.nlm.nih.gov/entrez/quer ... med_docsum says
The double-blind in danger: untoward consequences of informed consent.

Brownell KD, Stunkard AJ.

Patients and physicians correctly identified medication assignments in 70% of the cases in a double-blind trial of an appetite suppressant. The breach of the double-blind design may have had therapeutic consequences; correct identification was associated with favorable outcome. These findings suggest that requirements for describing the side effects of medications to patients before they give informed consent may help them guess which medication they receive and thus may influence the integrity of double-blind studies and the results of controLled trials.


It is a mistake IMHO to overvalue the meaning of a positive trial. It is still true after the trial that the drug may or may not help YOU, and given the way double blind trials are not so blind, every drug trialled probably has a positive impact from that expectation. And it may be true that the largest influence on the trialled drug then will come from the "pretrial expectation" that can be generated via research "leaks". One can see the effect of this when they read a post that says "I am trying desperately to get into the trial of (x)". How can anyone want, in an unbiased way, a drug that is not trialled yet? it is completely impossible for there to be any objective information out on it at that point. Any and all information is coming from commercially interested parties. That person has been grossly influenced somehow and has a huge positive expectation.

yet someoen could fairly say to me well you are taking antibiotics for MS you have this same expectation. Yes I sure do. And any result I have will be considered anecdotal because of that. But imagine anonymous poster above gets in trial "X" and is told that she can expect certain side effects and she, luckily enough, experiences them. Is her data objective? What does she report to her researcher? Does she gush to her evaluating researcher about how well she is doing? Is the researcher influenced by this? Of course!

Is my personal trial REALLY that different? Think about it: maybe not. If 70% of participants know they are getting thing "X" and also have positive expectation then it may be true that a majority of the effect is actually no better than anecdotal as well

I am waiting for research to finally answer the question as to what specifically causes MS. Only then will new drugs be more effectively targeted and we'll see trials with much higher effectiveness numbers.
That'd be good!

In the end every patient must try a given drug in a very unblinded trial on themselves. If it helps you, you have your answer.
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