sham treatment and placebo

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sham treatment and placebo

Postby scorpion » Thu Dec 09, 2010 3:21 pm

There has been a lot of confusion on here about the the term "placebo". Whether it be drug trials, CCSVI, etc. the below example shows why it is imperative to rule out a placebo effect before calling medication, surgeries, etc. a success.

The Placebo Effect of Surgery

In my recent comment...

"The human body has a spectacular ability to heal itself, when given time, clean food/water/air, and nurturing. Therapies, alternative and conventional, have an element of placebo. We think it was the chiropractor, the surgeon, the homeopathic remedy, the antibiotic that cured us. In actuality it was our body's natural healing apparatus."
I referred to surgery as having an element of placebo. It made me recall this passage from a book read long ago, "Health And Healing" by Dr. Andrew Weil. Here's an excerpt where he describes the placebo effect of surgery for angina:
"Angina pectoris had always been a medical problem until surgeons came up with operations to relieve it. One procedure that became fashionable in the 1950s was to open the chest and tie off the internal mammary artery, an artery supplying muscles of the inner chest wall. A branch of this vessel brings blood to the pericardium, the sac enclosing the heart. In theory, tying off the artery below this branch might increase blood flow to an ischemic heart. (The chest wall muscles can find alternative supplies.) Many patients reported disappearance or decrease of anginal pain on recovering from this traumatic operation.

As I explained in chapter 3, angina is notoriously responsive to placebo treatment. Might these patients have improved just because they underwent dramatic surgery? The ethics of controlled studies in this area are sticky, but eventually, a few surgeons put the procedure to a test by performing sham operations on some patients. The patients were told they were undergoing internal mammary artery ligation to bring new blood to their hearts, but, in fact, when their chests were opened, the artery was not tied off. The success rate of sham surgery in alleviating the symptoms of angina was equal to that of the real procedure, proving that this widely endorsed operation acted as a placebo treatment.

Undaunted, the surgeons next came up with a more elaborate procedure: internal mammary artery implant. They now cut the artery and inserted the cut end into a hole poked into the heart muscle, hoping it would sprout new branches to supplement the coronary arteries. Again, patients reported decreases in anginal pain. No one put this procedure to the test of comparison with sham surgery, but, since autopsy data later showed that the implanted arteries did not establish any new blood supplies in heart muscle, any success must also have been a placebo response."
Since Dr. Weil's writing, a more recent surgical intervention for angina - angioplasty with stenting (known under the umbrella term Percutaneous Coronary Intervention: PCI) - has also come into question. In a large clinical trial known as the COURAGE study, patients with chronic chest pain and "extensive coronary artery disease as seen on angiography" who received stents fared no better than those who received aspirin, statins, and/or blood-pressure-lowering drugs: ... rgery.html
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Postby rainer » Thu Dec 09, 2010 6:16 pm

Any result that is difficult to quantify i.e. pain or energy level, seems especially susceptible to this effect.

Of course then you get into the philosophical / ethical questions of placebo benefits being legitimate in of themselves.
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Postby ikulo » Thu Feb 03, 2011 12:29 am

Just wanted to post this tidbit on placebo. I was looking over an MSIF document that listed each type of treatment with the placebo results. Check here on page 20: Anyway, what you will see on the chart is that the annualized relapse rate varied in the studies between .73 and 1.28, and the treatment annualized relapse rate varied between .23 and .91.

Interestingly the relapse rate in the tysabri placebo group was actually better than the treatment arm of the Interferons. That is quite the deviation. Any ideas on why the tysabri would have such a low relapse rate in the placebo group? Could the act of having an infusion create a more powerful placebo effect than injections?
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