Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Within the European Union (EU), pharmaceutical licence holders have to make public information on potential adverse effects associated with medicines. EU guidance is that this information should include estimated frequencies of any effects; however, there is uncertainty about the most effective way to do this. In the UK two influential organisations, the MHRA and NICE, have advocated using risk expressions that combine a numerical estimator and a verbal term: e.g. "this side effect is common (it may affect more than 1 in 100 people)". However, there is no apparent evidence to support this recommendation and a concern is that the use of the verbal terms (very common, common, uncommon, rare, very rare) may lead to increased risk estimates. There is also a lack of evidence about the risk qualifier terms. In this case, the recommendation is to use the term 'may', although 'will' would seem more accurate.

Who can participate?
Adults accessing the study via two pages ( AND on the Cancer Help UK website.

What does the study involve?
Participants are randomly allocated to receive information on five side effects of Taxol using either a numerical term only or a combined numerical and verbal term, and using either the word 'will' or the word 'may'. Participants read the information and then estimate the frequency of the 5 side effects and of any side effect occurring. They also give estimates of the severity and 'harmfulness' of the side effects, using 5 Likert scales. Finally participants complete 8 questions intended to measure their numeracy skills.

What are the possible benefits and risks of participating?
Potential benefits of participating are to have a clearer understanding of the risks associated with the medicine, Taxol. There are no risks associated with taking part - just the time given to completing the questionnaire.

Where is the study run from?
The study is the result of a collaboration between researchers at the Universities of York and Leeds, and the website Cancer Help UK (owned by the charity Cancer Research UK). The data are held on a database at the University of Leeds. The PI, Dr Peter Knapp, is based at the University of York, UK.

When is the study starting and how long is it expected to run for?
January 2013 to April 2014

Who is funding the study?
1. University of Leeds (UK)
2. University of York (UK)

Who is the main contact?
Dr Peter Knapp

Trial website

Contact information



Primary contact

Dr Peter Knapp


Contact details

Department of Health Sciences
University of York
LS10 9DD
United Kingdom
+44 (0)1904 321675

Additional identifiers

EudraCT number number

Protocol/serial number

York-Leeds CRUK9

Study information

Scientific title

What is the effect of two framing variables on perceived risks associated with the medicine Taxol?



Study hypothesis

That participants' risk perceptions will not be influenced by two potential framing influences: first, providing frequency information using numbers alone or a combination of number and words; second, using different verbal qualifiers to convey risk.

Ethics approval

University of Leeds, Institute of Psychological Sciences research Ethics Committee, 22/06/2012, ref: 12-0127

Study design

Factorial trial (2x2) with concealed random allocation of individual participants

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

There is no PIS - that was approved by the REC. There is brief information on the website before people agree to take part. By agreeing to take part, people are confirming that they have received sufficient information about the study.




Information. (Risk frequency information presented in one of four ways).

There are four arms to the trial. Participants read the information about the medicines and then answer some questions about it. That is, 'follow-up' is immediate.
In all four arms of the trial participants receive information about 10 potential side effects of Taxol - the way that that risk is expressed varies across the four trial conditions.

The side effects:

1. May affect more than 1 in 10 people.
2. Very common: may affect more than 1 in 10 people
3. Will affect more than 1 in 10 people.
4. Very common: will affect more than 1 in 10 people.

(The incident rate bands vary according to the SE being portrayed).

The trial is evaluating the effect of adding verbal risk terms to the numerical information. Also, the use of the terms 'may' and 'will' to convey risk.

Intervention type



Drug names

Primary outcome measure

1. Estimated frequency of any side effect occurring
2. Estimates frequency of 5 individual side effects

Secondary outcome measures

1. Estimated severity and degree of harm from the side effects
2. Participants' numeracy

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Adults (aged 16 or over) accessing the study via two pages ( AND on the Cancer Help UK website.

Participant type


Age group




Target number of participants


Participant exclusion criteria

Does not meet inclusion criteria

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

University of York
LS10 9DD
United Kingdom

Sponsor information


University of York (UK)

Sponsor details

Department of Health Sciences
LS10 9DD
United Kingdom

Sponsor type




Funder type


Funder name

University of Leeds (UK)

Alternative name(s)

Funding Body Type

private sector organisation

Funding Body Subtype

Universities (academic only)


United Kingdom

Funder name

University of York

Alternative name(s)

The University of York

Funding Body Type

private sector organisation

Funding Body Subtype

Universities (academic only)


United Kingdom

Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2016 results in:

Publication citations

Additional files

Editorial Notes

16/01/2017: Publication reference added.