Condition category
Infections and Infestations
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Chlamydia is the most common bacterial infection that is transmitted sexually [Sexually Transmitted Infection (STI)] in the UK and is increasing in young people under the age of 25. The infection can be easily identified and treated but, if left untreated, may cause long-term negative health effects. Previous research have shown that mental health problems in young people, such as depression and anxiety, are related to greater risk of performing risky sexual behaviour and contracting STIs. There is a lack of research on the sexual risk behaviour of university students in the UK, even though the majority of university students typically fall into the 18-25 year age group that is at high risk of contracting sexually transmitted diseases, such as chlamydia. This study will find out the effects of receiving either an intervention based on the Theory of Planned Behaviour (TPB), a TPB intervention alongside making an if-then implementation intentions plan, or basic health information about getting tested for chlamydia on chlamydia testing beliefs, intentions and behaviour. The study will also find out the impact of anxiety and depression on the effectiveness of these interventions.

Who can participate?
All students registered with the University of Sheffield volunteers list, aged between 18 and 25.

What does the study involve?
Students who decide to take part will be asked to complete an online questionnaire at the start of the academic year to assess background information, anxiety, depression, sexual behaviour and testing history. They will then be randomly assigned to one of the experimental conditions after which they will complete the belief and intention measures. All participants will be asked to complete a further brief follow-up questionnaire at the end of the academic year to assess their sexual behaviour and whether they have been tested for chlamydia.

What are the possible benefits and risks to participating?
Getting tested for chlamydia can offer identification and treatment for chlamydia, reducing the risk of short-term and long-term health implications and preventing further spread of the condition. We hope the interventions will increase the uptake of chlamydia testing amongst students. In order to incentivise participation, participants will have the opportunity to be entered into a £50 prize draw after completing each questionnaire. Due to the nature of these studies, it is expected that some participants may wish to know more about chlamydia or wish to access information regarding where to get tested for chlamydia. Therefore, all participants will be provided with information at the end of their participation regarding where to get further information about chlamydia and where to access chlamydia testing. As these studies will also be asking participants about their mood, there may be occasions where they have indicated that they are struggling with symptoms of anxiety and/or depression. As a result we will also provide information regarding the University Counselling service and advise participants that if they feel they are struggling with
symptoms of anxiety and/or depression that they contact their GP for further support.

Where is the study conducted?
The study is conducted online and is managed by researchers at the University of Sheffield, UK.

When is study starting and how long is it expected to run for?
The study will start in September 2014 and it is expected to run until June 2015.

Who is funding the study?
The study is funded by the Clinical Psychology Unit, University of Sheffield, UK.

Who is the main contact?
Professor Paul Norman

Trial website

Contact information



Primary contact

Prof Paul Norman


Contact details

Department of Psychology
University of Sheffield
S10 2TP
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

A brief theory-based online intervention to increase uptake of chlamydia testing in university students aged 18-25


Study hypothesis

The study will compare the effectiveness of three experimental conditions (1. Theory-based messages, 2. Theory-based messages and an implementation intention task, 3. Basic information about chlamydia testing) on university students’ chlamydia testing beliefs and behaviour.

It is hypothesised that:
1. Participants who receive the theory-based messages (conditions 1 and 2) will report more positive beliefs and stronger chlamydia testing intentions than participants who receive basic information (condition 3).
2. Participants who receive the theory-based messages and the implementation intention task (condition 2) will report greater rates of subsequent testing behaviour than participants who receive just the theory-based messages (condition 1) or basic information (condition 3).

The study will also examine whether intervention effects are moderated by anxiety or depression.

Ethics approval

University of Sheffield, Department of Psychology Research Ethics Committee; 17/1/2014; ref. 2014-849

Study design

A between-participants design. Participants will be randomised to condition (theory-based messages, theory-based messages + implementation intention, basic information).

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format. Please use the contact details below to request participant information material




After completion of an online baseline questionnaire assessing demographics, anxiety, depression, sexual behaviour and previous testing for chlamydia, participants will be randomly assigned to one of three conditions.

1. Participants assigned to TPB-messages condition will be presented with information (video/text) based on the TPB targeting the key beliefs underlying chlamydia testing. The information (video/text) was developed on the basis of formative work that identified the key beliefs associated with university students’ chlamydia testing intentions.

2. Participants assigned to TPB-messages and implementation intentions condition, will be presented with the same information and then will be asked to form an if-then plan, stating where, when and how they intend to complete a chlamydia screening test in the event that they have had unprotected sex or sex with a new partner.

3. Participants assigned to the control condition will be asked to read basic/brief information about chlamydia testing.

All participants will then be asked to complete measures of beliefs and intentions regarding chlamydia testing. They will also be followed-up at the end of the academic year to assess their chlamydia testing behaviour.

Intervention type



Not Applicable

Drug names

Primary outcome measures

The experimental groups will be compared on the following primary outcome measures:

1. Chlamydia testing intentions (post-intervention).
2. Uptake of chlamydia testing in the event of having unprotected sex and/or a new sexual partner (at the end of the academic year).

Secondary outcome measures

The experimental groups will also be compared on the following secondary outcome measures:

1. Direct measures of the TPB (Ajzen, 1988) (post-intervention)
2. Belief strength (Ajzen, 1988) – beliefs targeted in the messages (post-intervention)

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

Students aged 18-25 attending the University of Sheffield

Participant type


Age group




Target number of participants

At least 158 at baseline.

Participant exclusion criteria

Not provided at time of registration

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Department of Psychology
S10 2TP
United Kingdom

Sponsor information


University of Sheffield (UK)

Sponsor details

Research & Innovation Services
New Spring House
231 Glossop Road
S10 2GW
United Kingdom

Sponsor type




Funder type


Funder name

University of Sheffield (UK) - Clinical Psychology Unit

Alternative name(s)

Funding Body Type

Funding Body Subtype


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

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes