Posted by SLS on May 26, 2001, at 11:23:00
In reply to NEJM Article says placebo effect small, posted by Jane D on May 24, 2001, at 11:31:51
> The NEJM just published an article claiming that the placebo effect, where you get better only because you believe you will, is actually very small.
>
> If I understand it correctly, the authors looked at a number of studies that included a control group that knew they were not being treated as well as the placebo group and found no difference in measurable things like blood pressure and only a small difference in things like pain that depended on the subjects report. Subjects that were not treated did get better but it happened whether or not they thought they were being treated meaning it was caused by random ups and downs of the illness, not power of suggestion.
>
> This fits with my experience. I have believed very strongly in drugs that did not work and gotten great relief from one that I expected nothing from. I've also been slightly offended by the implied suggestion that I couldn't tell what worked for me and what didn't.
>
> Any comments?
>
> Jane
>
> There is a description of the article on the NY Times web site at
> http://www.nytimes.com/2001/05/24/health/24PLAC.html
> (registration required but free and immediate)
>
> and the abstract is at
> http://www.nejm.com/content/2001/0344/0021/1594.asp
> (full text only for subscribers, alas)Hi Jane.
Thanks for the citation links.
It has always seemed to me that the placebo response rate of 30% reported for clinical trials of antidepressants was higher than I would expect intuitively given the way I personally experience depression and drug responses. Such a high response rate to placebo tends to make the active treatment seem less significant somehow.
Of great significance is the observation that the placebo response rate for the more severe or treatment-resistant depressions is very low; perhaps less than 10%.
I think that there are several contributing factors to the placebo "response" when dealing with depression.
1. The objective measurement of a subjective experience such as depression is difficult to quantify, and can involve bias on the part of both the patient and the investigator.
2. The nosological classification of depressive disorders is inexact. The criteria for choosing patients for inclusion in a study can differ from investigation to investigation, and is often overly broad or liberal.
3. Depressions more often have a fluctuating or episodic course. Some of those people who improve during a trial of placebo would have done so anyway, as this was the natural course of their illness.
4. A patient may experience great relief at the thought that they are receiving medical treatment that will end their pain.
5. One study I came across demonstrated that patients recruited through advertisements rather than consultation referrals tend to show a higher rate of early placebo response and are less depressed to start with. Many of the investigations published use recruits.
- Scott
poster:SLS
thread:64120
URL: http://www.dr-bob.org/babble/20010522/msgs/64323.html