Placebos and placebo effects II

The second GEBU article on placebos and placebo effects deals with the use of placebos in medical practice. It first examines the magnitude of and differences in the placebo response for two commonly used drugs, which clearly shows that there is no standard placebo effect or response. The physiological mechanisms found so far to be involved in the placebo response differ for the various disorders. Mapping these mechanisms will require more research. The article goes on to explain how the placebo response can be used in practice, and the associated consequences in terms of medical ethics. There is no such thing as a typical placebo responder. Although genotyping might in the future be able to help optimise treatments, its application in medical practice is still a distant prospect. Until such time, a care provider cannot determine at a glance whether a patient will respond better to treatment because he or she has a stronger placebo response. Possible factors that can be used to enhance the effects of treatment include personal characteristics of patients that affect compliance and their confidence in the treatment. In more general terms, the relation between care provider and patient has proved to be an instrument that can be used to influence the patient’s expectations and hence the placebo response. The form in which a drug is administered can also influence the placebo response, as it may strengthen or undermine the patient’s confidence in the treatment and hence their expectations. The current trend among care insurers to regularly change the brand they are willing to reimburse, resulting in changes in the drug’s external appearance, could thus have an unfavourable effect. A less easily modifiable way to increase the placebo response would seem to be that of conditioning patients, where negative expectations can undo the effect of positive conditioning. Non-drug treatments, such as psychotherapy or surgical interventions, are not discussed in the article, but they too may offer opportunities for optimising the placebo response.

In any drug therapy, part of the effect is due to the placebo response, regardless of the magnitude of the drug effect. Care providers often subconsciously influence this response, but the response can also be deliberately used to optimise a patient’s treatment. Using this option efficiently requires an understanding of the magnitude of the placebo response and the characteristics of typical placebo responders. If a patient is a placebo responder, this will make the treatment more effective than among non-responders, which is advantageous for both patient and care provider.

The Dutch Medical Treatment Contracts Act (WGBO) makes it difficult, though not impossible, for care providers to use placebos in their practice. The compulsory ‘informed consent’, which means the patient has to be informed about the nature of the treatment, affects the magnitude of the placebo response and can increase the nocebo response. Optimising drug therapy by increasing the placebo response, for instance by influencing the patient’s expectations, is not regarded as unethical. In addition, research has shown that the placebo response remains even if the patient is aware that he or she is receiving a placebo.

Research into the placebo effect is hampered by the fact that not all study designs are suitable to determine its existence and magnitude. Whereas the placebo response can be measured in two-armed studies, investigating the placebo effect requires three-armed studies. Furthermore, it is often impossible to use blinding, making the findings less reliable. Nearly all studies have concluded that more research into the placebo effect and placebo response is warranted. Well-designed studies have been scarce, which means that convincing conclusions can hardly ever be drawn. This implies that care providers currently have few concrete options for optimising treatment by enhancing the placebo response. The most feasible option is that of influencing the patient’s expectations about their treatment, an important precondition being the nature of the relationship between a care provider and their patients.

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