nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
See here for more discussion.

Wednesday, December 29, 2010

Placebos Work....And Your Point Is?

 
A flurry of media articles were published over the holiday proclaiming "Placebos actually work."

A study had been published PLoS One, Dec 22) that appeared to show when you give people a placebo for their medical problem a significant number will show a benefit even when they know it's a placebo.

How could this be?  Reading the news, you might get the impression that somehow patients are able to transform an inert substance into a therapeutic success by the force of their will, or some mysterious mental power; that we should look to harness this special ability.

Readers of Nostrums know that bias comes in many forms, of which placebo is only one.  Remove the placebo effect, and those other, less visible forms, emerge.

The news reporting was disturbing, but it was the holiday.  And for once, I promised myself--and family--that there would be no interruptions (ask my kids how many times they impatiently waited on Christmas day because Dad didn't get relieved from emergency room duty until 8AM).  So I let it go.

But, the frustration remains.  Here's a short description of what news readers were told (Science Daily, Dec 23),
...80 patients suffering from irritable bowel syndrome (IBS) were divided into two groups: one group, the controls, received no treatment, while the other group received a regimen of placebos -- honestly described as "like sugar pills" -- which they were instructed to take twice daily.  ...By the end of the trial, nearly twice as many patients treated with the placebo reported adequate symptom relief as compared to the control group (59 percent vs. 35 percent). Also, on other outcome measures, patients taking the placebo doubled their rates of improvement to a degree roughly equivalent to the effects of the most powerful IBS medications.
Put aside for the moment that with a study population of 80, the difference between the results in the control group and the "treatment" group was about 10 patients.  There's little you can conclude from such small numbers.

Put aside that we're dealing with a syndrome (IBS) that is characterized by abdominal pain, bloating, and discomfort...all of which are perceived subjectively.  That's not to say it doesn't exist and make life hell for sufferers, it just means that we're dealing with symptoms that are modified by things like the individual's sensitivity to pain, mental state, etc.  It's not as easy to measure quantitatively, compared to a throat culture or a cholesterol level.

Put aside that comparing a group that got "something" to a group that got "nothing" is...well...not really comparable.

Lastly, put aside that placebo studies tend to work mainly on symptoms like pain.  Even if there is something positive from placebo use, it aint gonna cure cancer...and it didn't cure the IBS.

Here are the other caveats left untouched by the media:

1.  People who suffer from chronic pain go through cycles where their symptoms are worse for a while, then get better, and so on.  If you treat someone during the worst part of the cycle--where they are most likely to seek help--they will tend to show a benefit as they move into their improvement phase.  Study their symptoms over long enough period of time, and the treatment benefit tends to go away as they move into the next, more painful cycle.  This study was way too short (three weeks!).

2.  Ask yourself what kind of patient will agree to enter a study where they are told that the treatment they are being given is of no benefit.  Does it select out those people who say, "No way.  I'm hurting and I don't want to waste my time on something that doesn't work"? This will skew the results toward those who are desperate enough to hope for improvement, no matter what.

3.  And then there's the Hawthorne effect.  Named after the factory in which the study occurred, this phenomenon is produced when participants know they are being observed in an experiment, and behave differently.  In the original experiment, investigators raised the light level in the factory and noted an improvement in the output.  They then lowered the light level, and output improved again!  The effect is also seen in medical trials; patients tend to report results differently when they know it's an experiment.  The tendency is for patients to show some impact just from being monitored closely:  "You know, now that I think on it, I do feel better."

The placebo effect is real, but it's not mysterious.  Other sources of experimental bias are also real, and they don't go away just because you've told patients they're taking a placebo.

If you want some positive conclusion from this study, it's that people are complex and bias is almost impossible to eliminate.

Doc D
 
 

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