July 2006

Placebo power

by Dr. Christopher Kent

Many scientists and clinicians consider the placebo‑controlled trial the "gold standard" for evidence‑based practice. Coulter [1] notes that according to The Office of Technology Assessment, "Objections are rarely if ever raised to the principles of controlled experimentation on which RCTs are based." Others have stated that placebo‑controlled trials are needed to provide data on effectiveness of active treatment. [2]

Interestingly, surgical procedures are often exempt from the scrutiny of placebo‑controlled trials. Ethical considerations are considered barriers to the use of placebo‑controlled investigations for surgical procedures. [3,4] There have been five studies where placebo surgery was used as a control. The placebo group generally did as well or better than the group receiving the real operation.

In 1939, a surgeon named Feischi developed a surgical procedure for angina pectoris. He reasoned that if the blood flow to the myocardium could be increased, the symptoms of angina would diminish. It was felt that ligating the internal mammary artery would increase myocardial blood flow. The clinical results were favorable, and the operation became popular, with three‑quarters of patients reporting improvement or elimination of symptoms. [5]

Twenty years later, the New England Journal of Medicine (NEJM) published the results of a placebo‑controlled trial of internal mammary artery ligation. [6] Of seventeen patients, eight got the actual operation. The other nine were anesthetized and got incisions, but nothing else. The fake operations worked as well as the real thing. As a result, internal mammary artery ligation surgery was soon abandoned.

The next wave of placebo surgery involved the human brain. Fetal pig nerve cells were implanted into the brains of 10 patients with Parkinson's disease. Eight patients had holes drilled into their heads, but received no implants. It was reported that "no significant improvement resulted from implanting the fetal cells of pigs into patient brains when compared with subjects who received placebo surgery." [7]

A second study, involving the implantation of stem cells from aborted human fetuses into the brains of patients with Parkinson's disease, was reported in the NEJM. [8] 20 of 40 patients received sham surgery, and 20 got the real thing. Holes were drilled into the skulls of the patients receiving sham surgery. Thankfully, the authors noted that "the dura was not penetrated." Some younger subjects were claimed to experience some benefit. Older subjects receiving the stem cells reported a worsening of their condition.

The latest study was a controlled trial of arthroscopic surgery for osteoarthritis of the knee. A total of 180 patients with osteoarthritis of the knee were randomly assigned to receive arthroscopic debridement, arthroscopic lavage, or placebo surgery. Pain and function were assessed over a 24‑month period. The result? "At no point did either of the intervention groups report less pain or better function than the placebo group." [9] This investigation followed a smaller pilot study with similar results. [10]

The notion of being subjected to unnecessary surgery is horrifying enough. However, that is only part of the story. According to one report, arthroscopic surgery for osteoarthritis of the knee is done on at least 225,000 Americans each year, termed 'a sham' by Dr. Baruch Brody, an ethicist at Baylor College of Medicine. [11] The cost of this intervention is estimated at $3.25 billion per year. [3]

Insightful researchers realize that the placebo is not merely a contaminant in an otherwise pristine experimental design. The placebo effect is another way of mobilizing the power of intent and expectation. Science has learned that, "Expectation releases substances, molecules, in your brain, that ultimately change your experience...The mind, it seems, may play a critical role in treating diseases. And its services come free of charge, with no co‑payment or deductible. Getting a person to boost their own machinery to improve health ‑‑ that's something that medicine needs to know." [12]

The power of the placebo cannot be denied. It unleashes the inherent recuperative powers of the body. Yet, the results of research using placebo surgery demand that we ask, "At what cost, and at what risk?" Keep this in mind next time someone tells you they "have to" have surgery. Where's the science? Or are anecdotes and conjecture good enough?

References

1. Coulter H: "The controlled clinical trial. An analysis." Washington (DC): Center for Empirical Medicine. Project Cure; 1991.

2. "Placebo controlled trials are needed to provide data on effectiveness of active treatment" (editorial). British Medical Journal 1996;313:1008.

3. Horng S, Miller FG: "Is placebo surgery unethical?" N Engl J Med 2002;347(2):137.

4. Weijer C: "I need a placebo like I need a hole in the head." J Law Med Ethics 2002;30(1):69.

5. Stolberg SG: "Sham surgery returns as a research tool." The New York Times. 4/25/99.

6. Cobb LA, Thomas GI, Dillard DH, et al: "An evaluation of internal mammary artery ligation by a double‑blind technic." N Engl J Med 1959;260:1115.

7. Hung M: "Placebo surgery gains wider acceptance." http://www.medscape.com/viewarticle/411258.

8. Freed CR, Greene PE, Breeze RE, et al: "Transplantation of embryonic dopamine neurons for severe Parkinson's disease." N Engl J Med 2001;344(10):710.

9. Moseley JB, O'Malley K, Peterson NJ. Et al: "A controlled trial of arthroscopic surgery for osteoarthritis of the knee." N Engl J Med 2002;347(2):81.

10. Moseley JB, Wray NP, Kuykendall D, et al: "Arthroscopic treatment of osteoarthritis of the knee: a prospective, randomized, placebo‑controlled trial. Results of a pilot study." Am J Sports Med 1996;24(1):28.

11. Kolata G: "A knee surgery for arthritis is called a sham." The New York Times. 7/11/02.

12. Guterman L: "Duping the brain into healing the body." The Chronicle of Higher Education. December 3, 2003.

(Dr. Christopher Kent, president of the Council on Chiropractic Practice, is a 1973 graduate of Palmer College of Chiropractic. The WCA's "Chiropractic Researcher of the Year" in 1994, and recipient of that honor from the ICA in 1991, he was also named ICA "Chiropractor of the Year" in 1998. He is director of research and a co‑founder of Chiropractic Leadership Alliance. An attorney as well as a chiropractor, Dr. Kent is a member of the California bar. With Dr. Patrick Gentempo, Jr., Dr. Kent produces a monthly audio series, "On Purpose," covering current events in science, politics and philosophy of vital interest to the practicing chiropractor. For subscription information call 800‑892‑6463.)