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Author Topic: Why the placebo "worked" in the xiaflex trial  (Read 4871 times)

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MikeSmith0

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Why the placebo "worked" in the xiaflex trial
« on: July 10, 2012, 09:05:16 PM »

The placebo injections appeared to have helped people in the trial (the Xiaflex group improved 37% and the Placebo group improved 21%), but there are uncelar biological reasons for this.  I have talked with a few doctors and below are some ideas about what may have happened.  The placebo in the xiaflex trial was injected with 1 tiny shot of a very small amount of saline-like substance.  So, why did it work?

1.  Confirmation Bias and highly imprecise measurement instrument - doctors want to see an improvement, so they error on the side of the penis improving over time when trying to measure a wobbly penis with a wobbly goniometer.  They took 3 measurements each time, but still - there is a psychological bias to see improvement & the measurement tool was highly  imprecise.  There are hundreds of psychological studies on confirmation bias - so even though it may seem unlikely - it is definitely a possibility in a situation like this where the measurement has a subjective component due to the doctor and the patient's response to prostaglandin that particular day.

2.  Worsening of Peyronies and diminished response to erection inducing drugs - some men respond less to the prostaglandin over time, particularly if their peyronie's is worsening.  The same dose will not create the same erection 1 year after peyronies has had a chance to destroy more of the penile elasticity.  So, the angle goes down - NOT because of the placebo, but because the penis is not as erect as it was at the start of the trial with the same dose of prostaglandin.  They are measuring a semi-flaccid penis at the end of the trial in placebo patients whose peyronies advanced, and they are told to keep the prostaglandin injection constant...so they cannot see the full erection which would show the same angle at the start of the trial. 

3.  Improved Peyronies - we know that some people spontaneously improve, though this is rare after 1 year - which was the minimum for trial subjects.  So, it's possible some people improved who had minimal plaques to begin with.  Plaque size was never measured.

Things that likely did not contribute to improvement


1. Modeling - the placebo subjects were asked to stretch their penis for a few minutes a day. We know that traction does not even work unless it is AT LEAST 4 hours a day.
2.  Swiss cheese effect - this doesn't work for verapamil (which is much more agressive and injected with a much thicker needle) so why would it work with a tiny needle injected in 1 spot with some saline.  If the "Swiss cheese effect" is real - then we can all get 20% improvements by paying $10 for a saline injection rather than $4-6000 for a xiaflex injection.  And, verapamil should work... so that's why I think it's not the reason. 

So, there are some thoughts on the big mystery.  I see no reason why the placebo should have helped at all - 20% is way too much.  What do you think?
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james1947

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #1 on: July 10, 2012, 09:59:34 PM »

I think that the difference between the Placebo and the Xiaflex group is because of the aggressive stretching (with popping like something broke) that folowed the Xiaflex injections after two days.

All the points you have mentioned are 100% right (in my opinion).

James
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Age 71, Peyronies from Jan 2009 following penis fracture during sex. Severe Erectile Dysfunction.
Lost 2" length and a lot of girth. Late start, still VED, Cialis & Pentox helped. Prostate surgery 2014.
Got amazing support on the forum

Luciano

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #2 on: July 11, 2012, 06:40:03 AM »

Stupid question, the 37% improvement with xiaflex injections is average right? so that means that some people could have had 74% improvement vs others could have had 0%. and also if some had worsening it would push down the average.
Or am I wrong?
Luc
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james1947

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #3 on: July 11, 2012, 07:04:09 AM »

It is not a stupid question Luciano and you are right it is an average improvement of 37%. This how I understand also from reading the report.

My private opinion as I have written already that maybe it is going down to the different doctors capability to inject in the correct place and to make the stretching with the popping noises correct.
Also in the average of the placebo (21%) it may go down to the same point.
Maybe we will not be surprised that from the Xiaflex average and the Placebo average some doctors achieved 74% improvements in both groups and some zero in both.
 
This point will never be clear as they will never report the improvements or failures as doctors related.
If we was knowing who they are, I am sure many of us will run to those doctors to inject us a $10 saline as MikeSmith0 has said and make us the stretching.
Saving on one injection between $4490 to $5990 is not bad at all.

James
 
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Age 71, Peyronies from Jan 2009 following penis fracture during sex. Severe Erectile Dysfunction.
Lost 2" length and a lot of girth. Late start, still VED, Cialis & Pentox helped. Prostate surgery 2014.
Got amazing support on the forum

Luciano

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #4 on: July 11, 2012, 07:52:17 AM »

Saving on one injection between $4490 to $5990 is not bad at all.

James
I am not sure about the pricing, I think that would be the price of full treatment.
Because here in europe xiaflex is sold under the tradename of xiapex. (for dupuytrens) I read in german forums that it was taken from the market in germany (for political reasons) and is only available in austria, price would be 1500 € (euros) that is $1800,-.
The pricing of xiaflex for Peyronies Disease would be the same (I think)
Luc
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james1947

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #5 on: July 11, 2012, 05:03:29 PM »

Still just $10 for the saline injection, so the saving will be "just" $1790.  :)
The prices I have mentioned are from our forum. One of our members get proposal from a US doctor for $6000 per Xiaflex injection.
I don't remember where is the post.
Maybe my pessimistic view is because the calcified plaques were excluded from the trial and my plaques are all calcified. :(


James
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Age 71, Peyronies from Jan 2009 following penis fracture during sex. Severe Erectile Dysfunction.
Lost 2" length and a lot of girth. Late start, still VED, Cialis & Pentox helped. Prostate surgery 2014.
Got amazing support on the forum

jackp

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #6 on: July 11, 2012, 08:35:53 PM »

Mike

The placebo did not work!!!!!

About 1/3 of men with peyronies, are like myself, the curve will straighten on its own in about 18 months. It happens spontaneously for us with no medical intervention.

IMHO the trial has a major flaw. It does not take into account the fact that in 1/3 of men the peyronies curve will straighten without medical intervention.

By the way my peyronies happend all of a sudden about 20 years ago and there was none of these medicines or supplements available. Only Vitamin E and Potaba.

Jackp
http://jackp-penileimplant.blogspot.com/
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MikeSmith0

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #7 on: July 16, 2012, 02:16:07 PM »


About 1/3 of men with peyronies, are like myself, the curve will straighten on its own in about 18 months. It happens spontaneously for us with no medical intervention.


Yes, agreed - that was # 3 in my post..but it would also happen in the xiaflex group so that basically cancels it out.
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jackp

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Re: Why the placebo "worked" in the xiaflex trial
« Reply #8 on: July 19, 2012, 02:50:06 PM »

Mike

I have been in the hospital but am home now. Sorry for the late responce.

See the PM I just sent you.

Jack
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