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Table 2 Core components of scripted interactions between study clinicians and study participants in each arm

From: Open-label versus double-blind placebo treatment in irritable bowel syndrome: study protocol for a randomized controlled trial

Open-label placebo
Interaction is geared toward making participants comfortable taking open-label placebo and reducing negative feelings about placebo. Specifically, patients will be told the following four points:
1. In clinical trials, IBS patients treated with placebos often improve nearly as much as patients on active medication
2. In order to reduce concern that that any placebo effect a participant might experience is “all in the head,” classical conditioning (“like Pavlov’s dogs”) will be suggested as a possible mechanism to explain how such self-healing can happen automatically
3. To suspend disbelief and encourage an open mind about the effectiveness of the treatment, patients will be told that positive expectations may be helpful, but it is normal to have doubts about open-label placebo. We can understand why patients might think the study is unusual
4. To encourage adherence, patients will be told that it is most important to take the pills faithfully. Research shows that patients who are more adherent – even to placebo – improve more than those who are less adherent
5. Participants are provided with reassurance that they may not notice changes right away. They are informed that some people respond to placebo “gradually” and others respond “quickly” and that this varies across individuals
Double-blind placebo and double-blind peppermint oil
1. Provide rationale for doing a double-blind experiment and the principle of equipoise
2. Provide a rationale for why peppermint oil might be effective: “Peppermint oil has been used for many years to ‘soothe’ the GI tract and is known to reduce contractions or spasms in the GI tract”
3. Explain that peppermint oil in IBS has never been tested in the USA
4. Provide a rationale for why placebo might be effective: “In early clinical trials IBS patients treated with placebos often improve nearly as much as patients on active medication”
5. Participants are provided with reassurance that they may not notice changes right away. They are informed that some people respond to placebo “gradually” and others respond “quickly” and that this varies across individuals
No-treatment control
1. Explain the importance of this research to develop effective treatments for IBS
2. Explain that it is critical to measure the normal waxing and waning of IBS symptoms in the no-treatment control group in order to understand the placebo and peppermint effects detected in the other arms of the study
3. Highlight the importance of not changing anything that they are regularly doing for the IBS during the trial
4. Explain that the study physician will provide some specific suggestions and options at the end of the trial
  1. GI gastrointestinal, IBS irritable bowel syndrome