Each morning at breakfast, my wife reminds me to take a mysterious gray tablet--the nature and purpose of which are unknown to me. I am still a volunteer in the ongoing Physicians’ Heath Study, a clinical trial that began in 1982 and has already shown that a daily aspirin can help prevent heart attacks.
Indeed, most people think of a placebo as the “dummy pill” used in controlled clinical trials. Volunteers are randomly divided into two groups. One group gets the drug being studied while the other gets the placebo, a look-alike, inert substitute. Neither the researchers nor the participants know which is which. At the end of the trial, the code is broken and the drug’s effect is compared with that of the placebo. But placebos alone can exert powerful effects on people and may have a place in settings other than clinical trials. And doctors and patients may be able to harness that power to good effect.
PLACEBO POWER
So to prove that a new medication is truly superior to a placebo, drug studies usually have to be quite large and well thought out. And it’s important to know how well the placebo fared. The smaller the difference between the placebo and the drug, the greater skepticism you should have about the drug.
It’s also important to keep in mind how the placebo was administered. That’s because the placebo effect usually conforms to a strict pecking order: Intravenous placebos have a stronger effect than those given by injection, which, in turn, are stronger than those taken by mouth. So it’s not surprising, for example, that acupuncture has been found to be better than oral pain medication in some studies. But when acupuncture is compared with sham acupuncture for certain conditions--in which practitioners insert needles but not in the specific locations called for by acupuncture theory--the benefit often vanishes.
Placebos can play a role in testing surgical procedures, too. A few years ago, for example, researchers performed sham arthroscopic knee surgery--complete with sedation and superficial incisions--to disprove the effectiveness of a popular knee operation used for osteoarthritis. And in the days before informed patient consent, sham surgery was used to discredit even more invasive procedures, including a chest operation for heart pain and the removal of a neck nerve for asthma relief.
POSITIVE ATTITUDE
Sometimes the placebo effect stems not from a pill or treatment but from the patient’s biases. A study published in March showed that expensive placebos are better than cheap ones. In another example, medical students in one study were given packets of red or blue inert tablets and told they were evaluating a new stimulant and a new tranquilizer. Those taking the red pills reported stimulant effects while those taking the blue ones felt depressed--reactions compatible with their association with the colors red and blue. Those who took a double dose of the pills had a stronger response than those who took only one.
In clinical practice, the most important placebo effect may well be the doctor’s attitude. In a British study, patients with various symptoms were divided into two groups, only one of which received firm assurance from the doctor that they would soon be well. Half the patients in each group were then also “treated” with a placebo, while the other half were not. The doctors’ positive attitude yielded a higher incidence of symptom improvement in both groups.
That research suggests that it certainly pays to approach health care with a positive attitude and choose treatments that you have confidence in. More complicated is whether it’s appropriate for doctors to sometimes “prescribe” placebos to their patients. Recent surveys in this country and abroad have shown that practice to be fairly common. Though I’ve never taken that step myself, I think it might be appropriate in certain instances--as long as it doesn’t add to the cost of treatment, conceal serious illness, or have the potential to do harm.
This article first appeared in the May 2008 issue of Consumer Reports on Health.
