All doctors are aware of the placebo effect. We were educated on this concept as we went through chiropractic school. The best research studies utilize the placebo effect to compare a specific treatment to a sham control.Various definitions of placebo effect exist, from "improvement in the condition of a patient that occurs in response to treatment but cannot be considered due to the specific treatment used"1 to "the beneficial effect in a patient following a particular treatment that arises from the patient's expectations concerning the treatment rather than from the treatment itself."2
This is a very simplistic and often inaccurate view of the placebo effect. Current research is turning this concept on its head and prior views of the placebo effect are changing. New research is showing that the placebo effect in pharmaceutical studies is actually increasing, to the point that if drugs that had previously been approved were tested today, they would not pass.
The placebo effect may not be as simple as we originally thought. To what extent does the placebo effect impact our interaction with our own patients? If the placebo effect can be enhanced, can it be used as another tool in our treatment? Did you know that taking two placebo dummy pills will trigger a bigger response than just one? Are you aware that withdrawal symptoms can occur if you take away a sham treatment? This article explores all these issues. The results may surprise you.
True vs. Perceived Placebo Effect
When we talk about the placebo effect of a treatment or clinical trial, we fail to take into consideration factors other than the direct effect of the placebo. That's why placebo effect is broken down into true versus perceived placebo effect. According to Ernst, et al.,3 the perceived placebo effect is what we commonly assume it to be, which is the simple response observed in the placebo group. The true placebo effect, however, equals this response minus other effects, which can vary greatly.
The extent of the true placebo effect can depend on such things as the attitude of the doctor or therapist (toward the treatment and patient); the attitude of the patient (toward their own health, the doctor or therapist, and/or the type of treatment); the conditioning of the patient (their suggestibility); and the type of treatment (its mechanism, as well as impressiveness, invasiveness, perceived plausibility, experience, cost, etc.).4
Placebo Effects Occur in Clinical Practice, Even If No Placebo Is Given
Once you understand the multifactorial basis of placebo, you can understand that the effect is not only localized to research studies. According to Finness, et al. (2010), "research shows that placebo effects are genuine psychobiological events attributable to the overall therapeutic context."5 Hence, placebo effects exist in clinical practice, even if no placebo is given.
Recently, a study by Kaptchuk from Harvard University showed that administering a placebo and telling the patient about it actually led to significant improvements.6 One group was provided with pills described as "sugar pills" claimed to treat irritable bowel syndrome. The patients were directly told that they were getting a placebo. Fifty-nine percent of the patients improved. Another group was provided with no treatment. Thirty-five percent of those patients improved.
How was it possible to have such significant improvements even though the patients knew they were getting a sugar pill? As discussed, placebo effect consists of many factors. In this case, patients were told that placebos have actually been shown to be effective in many clinical studies. This may have set up expectations of treatment. In addition, both of these groups received medical attention from doctors, which also factors in the doctor-patient interaction, beliefs of the doctor and patient, etc. Research has already shown that verbal suggestions can positively or negatively affect the outcome of treatment.7
Placebos Are Getting More Effective (Beyond the 30 Percent Assumption)
The experiment by Dr. Kaptchuk isn't a random, isolated case. Now that we know additional factors such as expectation of treatment can induce significant changes, the pharmaceutical industry is beginning to face hurdles in getting drugs to market. From 2001 to 2006, the number of new products cut after phase 2 clinical trials (which is when the drugs are first tested against placebo) rose by 20 percent.8 The failure rate in phase 3 trials increased by 11 percent, mainly due to poor showings against placebos. Half of all the drugs that fail in late-stage trials drop out due to the inability to beat sugar pills.
The surprising fact is that drugs that were once approved, like Prozac, are now showing reduced positive outcomes in follow-up studies. In fact, a study by Kirsch, et al. (2009) showed that most trials failed to show a significant advantage of SSRIs over placebo, and that the differences between drugs and placebo were not clinically significant for most depressed patients.9 (The study concluded that exercise and psychotherapy shows benefits that are at least equal to those of antidepressants.)
Integrating Placebo Research Into Clinical Practice
Placebo is no longer considered a "fake treatment." Drugs are becoming less capable of beating out sugar pills. Pharmaceutical companies understand the power of the placebo effect; that's why they spend considerable time and investment in picking the right color and shape for their pills, since this alone can produce additional benefits.
A study by Tilburt, et al. (2008)10 surveyed 1,200 internists and rheumatologists in the U.S. About half of the doctors reported prescribing placebo treatments on a regular basis, with 62 percent believing the practice to be ethically permissible. Similar results have been noted in Germany, where the German Medical Association recently recommended the use of placebos in the treatment of certain conditions. As long as the patient was notified they were receiving a placebo, there were no ethical concerns.
Prescribing placebo treatments is an ethical question and requires discussion that is beyond the scope of this article. However, considering that there is valid research into multiple factors affecting treatment outcome, how does that influence your approach to your patient? These findings suggest that integrating certain approaches can actually enhance the total treatment outcome. Here are some suggestions:
The doctor's belief in the success of their treatment outcome is a factor that must be considered. This is nothing new to doctors of chiropractic, and it now appears that our strong belief in our treatment philosophy may actually translate into a stronger belief in treatment expectations. If a patient senses your passion and conviction for your treatment approach, this will only help increase treatment success. This is one of the biggest strengths of the chiropractic profession. Now, there may be some evidence of the effectiveness of our approach to our patients as compared to the allopathic profession.
Verbal suggestions of positive treatment outcome also can enhance the effects, as seen in some of the research referenced here. I've been able to watch many doctors in practice over the years. The one characteristic of successful treatment that has always stood out is the positive reinforcement that was provided to the patient. Doctors who continually provide positive feedback and support will instill this positive expectation in the patient.
Some of us have gotten used to practicing without a "white coat" and even having patients call us by our first name. I am the first to admit being guilty of this. However, studies show that the patient's perception of the treating health professional can enhance their belief in the treatment approach. A doctor in a white coat, believe it or not, produces feelings of comfort in most people. The trust and credibility factor increases. Knowing what we know now regarding the placebo factors, it may be time to ensure that our outward impression echoes high professionalism and credibility.
The placebo effect is not as simple and straightforward as it once appeared. Pharmaceutical companies struggle to keep up with a more effective placebo effect. Half of the medical profession in certain specialties admit to using the placebo effect to treat patients, while other medical associations remain critical of such practices. We are also beginning to realize that a doctor's simple approach to care can either enhance or limit the results you may get with your treatments.
Instead of developing a pessimistic attitude toward such findings, embrace some of the valuable information and use it to enhance your already-effective treatment regimens for the benefit of the patient. As the placebo effect shows, there's no room for pessimism when it comes to patient care.
- Merriam-Webster Dictionary (online): definition of placebo effect.
- TheFreeDictionary.com; definition of placebo effect. www.thefreedictionary.com
- Ernst RE. Concept of true and perceived placebo effects. BMJ, 1995;311;551-3.
- Turner JA, et al. The importance of placebo effects in pain treatment and research. JAMA, 1994;271:1609-14.
- Finniss DG, et al. Biological, clinical, and ethical advances of placebo effects. Lancet, Feb. 20, 2010;375(9715):686-95.
- Kaptchuk TJ, et al. Placebos without deception: a randomized controlled trial in irritable bowel syndrome. PloS One, Dec. 22, 2010; 5(12):e15591.
- Laarhoven AI, et al. Induction of nocebo and placebo effects on itch and pain by verbal suggestions. Pain, February 2011; Epub ahead of print.
- Silberman S. "Placebos Are Getting More Effective. Drug Makers Are Desperate to Know Why." Wired, Aug. 24, 2009.
- Kirsch I. Antidepressants and the placebo response. Epidemiol Psychiatr Soc, Oct-Dec 2009;18(4):318-22.
- Tilburt JC, et al. Prescribing "placebo treatments": results of national survey of US internists and rheumatologists. BMJ, Oct. 23, 2008;337:a1938.
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