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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The assessment of blinding: the case of caffeinated and de-caffeinated coffee
Scientific title
Can healthy individuals detect the replacement of caffeinated coffee with decaffeinated coffee
Secondary ID [1] 280992 0
New secondary ID. Please modify.
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
removal of coffee from diet 3701 0
Condition category
Condition code
Other 3865 3865 0 0
Research that is not of generic health relevance and not applicable to specific health categories listed above
Public Health 4036 4036 0 0

Study type
Description of intervention(s) / exposure
Replacing regular coffee with supplied decaffeinated coffee for 1 week. As per inclusion criteria, participants should consume at least 2 cups per day, but no set requirement to consume a specified amount. Both Caffeinated and Decaffeinated coffee will be supplied by The Coffee Roaster.
Intervention code [1] 3571 0
Comparator / control treatment
Replacing regular coffee with supplied caffeinated coffee for 1 week. As per inclusion criteria, participants should consume at least 2 cups per day, but no set requirement to consume a specified amount. Both Caffeinated and Decaffeinated coffee will be supplied by The Coffee Roaster.
Control group

Primary outcome [1] 4767 0
Assessment of blinding using self completed questionnaires, asking "what type of coffee do you think you are drinking"
Timepoint [1] 4767 0
Day 1, day 3 and day 7
Secondary outcome [1] 8054 0
Assess what factors lead to unblinding using self completed questionnaires asking "why do you think you are drinking this type of coffee?"
Timepoint [1] 8054 0
Day 1, Day 3 and Day7

Key inclusion criteria
18 years or older, Drink at least 2 cups of caffeinated coffee per day, ability to personally collect coffee from research staff, have internet access
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
people will be excluded if they do not meet inclusion criteria

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants register online, once eligible will be allocated to the next intervetion group as per randomisation schedule. This schedule will be concealed from investigators until allocation is required using sealed opaque envelopes.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
computer generated block randomisation.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 3879 0
Name [1] 3879 0
Australian Federation of University Women River Group
Address [1] 3879 0
Research Office
University of Sydney,
NSW 2006
Country [1] 3879 0
Primary sponsor type
A/Prof Alex Barratt
Edward Ford Building (A27)
University of Sydney
NSW 2006
Secondary sponsor category [1] 3483 0
Name [1] 3483 0
A/Prof Rob Herbert
Address [1] 3483 0
The George Institute
PO Box M201
Missenden Rd,
Camperdown NSW 2050
Country [1] 3483 0

Ethics approval
Ethics application status
Ethics committee name [1] 5931 0
University of Sydney Human Research Ethics Committee
Ethics committee address [1] 5931 0
Room 313, OTC (A22)
University of Sydney NSW 2006
Ethics committee country [1] 5931 0
Date submitted for ethics approval [1] 5931 0
Approval date [1] 5931 0
Ethics approval number [1] 5931 0

Brief summary
This is a preliminary study to test methodology for a large intervention trial to be conducted later. This study aims to determine whether participants can be adequately blinded in a study where decaffeinated coffee and caffeinated coffee are the intervention and control conditions. In this study, participants will be randomized to receive either caffeinated or decaffeinated coffee, and be provided with enough coffee for a week. Participants will be asked to replace their regular coffee with the study coffee for one week, and refrain from consuming any other forms of caffeine (tea, cola, chocolate etc). They will not be told which coffee they are drinking, and, at various times throughout the week, they will be asked to guess what coffee they are drinking.
Trial website
Trial related presentations / publications
Mathieu E, Barratt A, McGeechan K, Herbert R. (2012) Blinding of participants in trials assessing the impact of caffeine removal on health outcomes: the results of an online randomised controlled trial. Australiasian Epidemiologist. 19 (1) April, 28-32
Public notes

Principal investigator
Name 28939 0
Address 28939 0
Country 28939 0
Phone 28939 0
Fax 28939 0
Email 28939 0
Contact person for public queries
Name 12096 0
Erin Mathieu
Address 12096 0
Edward Ford Building (A27)
The University of Sydney, NSW 2006
Country 12096 0
Phone 12096 0
Fax 12096 0
Email 12096 0
Contact person for scientific queries
Name 3024 0
Erin Mathieu
Address 3024 0
Edward Ford Building (A27)
The University of Sydney, NSW 2006
Country 3024 0
Phone 3024 0
Fax 3024 0
Email 3024 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary