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Trial registered on ANZCTR

Registration number

ACTRN12620000232932

Ethics application status

Approved

Date submitted

13/02/2020

Date registered

25/02/2020

Date last updated

8/11/2021

Date data sharing statement initially provided

25/02/2020

Type of registration

Prospectively registered

Titles & IDs

Public title

How do different message framing manipulations influence the effects of active placebos?

Scientific title

How does positive and negative message framing affect the placebo effect in a model of active placebos for sleep difficulty? A randomised controlled study in sleep-impaired adults

Secondary ID [1]

None

Universal Trial Number (UTN)

Nil known

Trial acronym

Nil known

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Sleep difficulty

Insomnia

Condition category

Condition code

Mental Health

Other mental health disorders

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Participants will be recruited under the guise of a study testing a new formulation of an antihistaminic drug containing beetroot extract as an antioxidant efficacy booster, but no active treatment is actually delivered. Instead, after one week of baseline measures participants will be randomised to one of four groups: three active placebo groups that receive either a positive, negative, or no message framing, or to a no-treatment control group. Message framing is a process whereby communicators act to construct a point of view that encourages the facts of a given situation to be interpreted by others in a particular manner. The positive message framing will inform participants that the experience of the target side effect, i.e. red-ish urine means that their body has absorbed and metabolised the medication well and the medication is likely to improve their sleep. The negative message framing will inform participants that the experience of the target side effect, i.e. red-ish urine means that their body has not absorbed and metabolised the medication well and the medication is not likely to improve their sleep. After the randomisation participants in the placebo groups will be handed an information sheet about the new formulation under investigation that will contain the message framing. After participants have read the message framing in the presence of the psychologist conducting the experiment, he will ask if they have any questions, clarify potential questions and repeat the most important parts of the information, verbally repeating the message framing. Participants only receive the message framing on one occasion during the second study visit in written and verbal form, they will not be reexposed to the message framing. Participants randomised to the active placebo groups will be blind towards their framing condition, and told they are receiving an antihistaminic drug. The no-treatment control group will be told that they will not receive treatment and will instead serve as a control group for the natural course of their sleep difficulty and daily symptoms.

The placebo capsules will be made of gelatine. The active placebo groups will receive four capsules per day for 7 nights containing each 625 mg of the food colour E 162, i.e. beetroot extract and 125 mg oxalic acid to stabilise and guarantee the absorption of the beetroot extract. The intention of the active placebo is to produce beeturia, i.e. a red-ish colouration of the urine to simulate side effects.
Adherence to the capsules will be assessed using a daily participant diary. Additionally, participants will need to return the capsule container containing all capsules they have not taken at the end of the study.

Intervention code [1]

Treatment: Other

Comparator / control treatment

Active placebo group with no message framing and no-treatment group. Placebo treatment will consist of four gelatine capsules per day for 7 nights containing each 625 mg of the food colour E 162, i.e. beetroot extract and 125 mg oxalic acid

Control group

Placebo

Outcomes

Primary outcome [1]

Insomnia severity assessed using the Insomnia Severity Index (ISI)

Timepoint [1]

Baseline (assessed at a single timepoint on the day starting treatment, for the 7 nights period prior to receiving treatment)
Treatment (assessed at a single timepoint on the day after finishing 7 nights of treatment, for the 7 nights period receiving treatment)

Primary outcome [2]

Reports of daily bothersome of red urine colouration assessed as part of an amended 10-item version of the General Assessment of Side Effects (GASE). We shortened the GASE to only include the most relevant items and added a question regarding urine colouration – the target side effect. We assessed how bothersome the complaints are on a visual analogue scale (VAS) ranging from 0 (= “not bothersome at all”) to 100 (= “absolutely bothersome”), with 33 (= “mildly bothersome”) and 66 (= “moderately bothersome”)

Timepoint [2]