Elsevier

The Lancet Neurology

Volume 3, Issue 11, November 2004, Pages 679-684
The Lancet Neurology

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Overt versus covert treatment for pain, anxiety, and Parkinson's disease

https://doi.org/10.1016/S1474-4422(04)00908-1Get rights and content

Summary

The recent introduction of covert administration of treatment to biomedical research has produced some interesting results, with many clinical and ethical implications. Concealed treatment has been used in people with nervous system conditions including pain, anxiety, and Parkinson's disease. The main finding is that when the patient is completely unaware that a treatment is being given, the treatment is less effective than when it is given overtly in accordance with routine medical practice. The difference between open and hidden administrations is thought to represent the placebo component of the treatment, even though no placebo has been given. The decreased effectiveness of hidden treatments indicates that knowledge about a treatment affects outcome and highlights the importance of the patient-provider interaction. In addition, by use of covert administration, the efficacy of some treatments can be assessed without the use of a placebo and associated ethical issues.

Section snippets

Informed consent

Informed consent is an important issue in open versus hidden treatment methods. Different approaches are used to obtain full, informed consent and there is no general rule. Most study participants are told that they could receive either an active drug, a placebo, or nothing, thus giving their informed consent to receive different treatments. When drag administration is hidden, participants believe that nothing is being given. For example, postoperative patients are told that they could receive

Open versus hidden injections of analgesic and antianxiety drugs

In the 1980s and 1990s, some studies were done in which analgesic drugs were delivered by machines through hidden infusions.8, 9, 10, 11 Infusion of a drug can be hidden by use of a computer-controlled infusion pump that is preprogrammed to deliver the drug at the desired time. Importantly, the patient does not know that any drug is being injected. This hidden procedure is done easily in the postoperative phase; the computer-controlled infusion pump delivers the painkiller automatically,

Open versus hidden deep brain stimulation in Parkinson's disease

We have applied the open—hidden method of study to the treatment of Parkinson's disease, specifically deep brain stimulation (DBS) of the subthalamic nucleus (STN). Two types of evidence suggest that hidden DBS is less effective than open treatment: study of stimulation with macroelectrodes in the postoperative phase13, 14 and study of autonomic and emotional responses to intraoperative stimulation with microelectrodes (figure 4).15

Firstly, we studied ten patients with idiopathic Parkinson's

Clinical implications

Although the evidence for differential effects of open and hidden treatments is limited to disorders involving the nervous system, and thus is not generalisable to all medical and surgical treatments, these provocative studies have two major findings. First, although many factors and variables may contribute to the differences between the outcomes of covert and overt treatments, certainly the awareness of the treatment, the presence of the therapist, and the expectation of the outcome are

Ethical considerations for clinical trials

The ethics of the open-hidden methods is relevant beyond routine medical practice and involves many parts of biomedical research. The use of placebos in clinical trials is still the focus of a hot debate and lively discussion. Critics of placebo-controlled trials have condemned the use of placebos because withholding proven, effective treatment results in suboptimum treatment. In other words, placebo groups do not receive the best treatment available. The World Medical Association (WMA)

Conclusions

We believe that the open-hidden approach can be used to address many unanswered questions, including nature of the placebo effect. When we measure the difference between open and hidden treatments, the term placebo effect is misleading because no placebo has been given. Therefore, the difference could be better described as the psychosocial component of treatment that comes from patient knowledge that they are receiving treatment. Our research shows that administration of drugs or brain

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