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
Sexually transmitted infections (STIs) are common in young people. Easy-to-treat conditions such as chlamydia or gonorrhea are particularly common, and can lead to major health problems if left untreated. Practicing safe sex by using condoms and getting tested for STIs before they stop using condoms with a new partner, lowers the risk of getting an infection. Likewise, people with an infection are less likely to get another infection if they tell their partner. These practices can be very difficult for young people however. The use of text messages offering support has been shown to be very effective in other areas, such as quitting smoking, as so it is possible that it could also help encourage safe sex, getting tested for STIs and helping people to tell their partner if they are infected. The aim of this study is to find out whether delivering support using text messages over the course of one year is an effective way of reducing STIs by promoting safe sex and regular STI testing.

Who can participate?
Young adults aged between 16 and 24 who have had a positive chlamydia or gonorrhoea test in the last two weeks and own a mobile phone.

What does the study involve?
Participants are randomly allocated to one of two groups. Participants in the first group receive regular text messages for one year (one-two per day for one month, two-three per week for the second month and then two-five per month for the rest of the study). These messages are tailored to individual participants based on gender, sexual orientation and which STI they have been diagnosed with. The messages contain information about treatment for their STI as well as promoting condom use to encourage safe sex. The messages also offer support on how to tell their partner so that they can be tested and treated. Participants in the second group receive a monthly text message for a year, asking them to provide information about any changes in the contact details. These participants receive usual care and are free to seek treatment and support as needed. After one year, participants are re-tested in order to find out how many have an STI. The number of participant’s partners who also came for treatment is also recorded.

What are the possible benefits and risks of participating?
Participants may benefit from the trial as they may find the messages helpful and may learn about safer sex behaviours. There are very few risks in taking part. Completing the questionnaires and providing a sample will take up some time. It is possible that the messages could be read by someone other than the participant. Participants are advised to password-lock their phones and delete messages after they read them. Data will be collected regarding whether other people viewed messages and whether the participant was happy/unhappy about this. Data will be collected about involvement in road traffic accidents as they are the only demonstrated harm resulting from text messaging.

Where is the study run from?
London School of Hygiene and Tropical Medicine (UK)

When is the study starting and how long is it expected to run for?
April 2016 to March 2018

Who is funding the study?
National Institute for Health Research (UK)

Who is the main contact?
Main contact as of 18/12/2018:
Kimberley Potter

Previous main contact:
Miss Rebecca Matthews

Trial website

Contact information



Primary contact

Ms Kimberley Potter


Contact details

Clinical Trials Unit (CTU)
Department of Medical Statistics
London School of Hygiene and Tropical Medicine
Keppel Street
United Kingdom
+44 207 7927 2473

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Safetxt: A randomised controlled trial of an intervention delivered by mobile phone messaging to reduce sexually transmitted infections (STI) by increasing sexual health precaution behaviours in young people


Study hypothesis

The aim of this study is to establish the effectiveness of a safer sex intervention delivered by mobile phone messaging on STI infection at one year; partner notification and condom use at 4 weeks; and partner notification, condom use and STI testing at one year.

Ethics approval

London - Riverside Research Ethics Committee, 16/10/2015, ref: 15/LO/1665

Study design

Randomised controlled trial

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 a patient information sheet


Topic: Infectious Diseases; Subtopic: Infectious Diseases; Disease: Infectious Diseases and Microbiology


Participants will be randomly allocated, using a remote computer based randomised system, to a safer sex intervention delivered by text messaging or to a control group. The allocation will be by simple randomisation.

Control group: Participants receive a monthly text message asking the participant to provide information about changes in postal or email addresses

Intervention group: Participants receive regular messages delivered by text message to influence safer sex behaviours. The intervention employs education, enabling and incentivising behaviour change functions and twelve behaviour change techniques identified in effective face to face safer sex interventions. The information on safer sexual practices is in accordance with existing guidelines. The intervention text message content has been developed in collaboration with young people and has been shown to be acceptable, comprehensible and relevant.
Participants will be sent messages at the following frequencies:
1. 4 messages per day for days 1-3
2. 1-2 messages per day for days 4-28
3. 2-3 messages per week for month 2
4. 2-5 messages per month for months 3-12

Intervention type



Drug names

Primary outcome measure

Cumulative incidence of Chlamydia and gonorrhoea infection at one year assessed by NAAT (nucleic acid amplification test) tests: urine for men with pharyngeal and anal swabs for MSM (men who have sex with men) and self-taken vulvo-vaginal swab for women.

Secondary outcome measures

1. Clinic attendance by partner for treatment is determined at four weeks
2. Whether participants took the treatment and avoided sex for 7 days after treatment is determined at four weeks

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Aged 16 to 24 inclusive
2. Received a positive chlamydia or gonorrhoea test result or have been diagnosed with NSU in the last 2 weeks
3. Own a personal mobile phone
4. Able to provide informed consent

Participant type


Age group




Target number of participants

Planned Sample Size: 6250; UK Sample Size 6250

Participant exclusion criteria

Known to be a sexual partner of someone already recruited to the trial.

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

London School of Hygiene and Tropical Medicine
Keppel Street
United Kingdom

Sponsor information


London School of Hygiene and Tropical Medicine

Sponsor details

Keppel Street
United Kingdom

Sponsor type




Funder type


Funder name

National Institute for Health Research

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

Federal/National Government


United Kingdom

Results and Publications

Publication and dissemination plan

The research findings will be published in high impact research journals and presented at international conferences. Findings will be disseminated to all service collaborators and participants in the trial, using our existing communication links. In addition, research findings will be presented to the general public via the media (newspaper, radio and TV). The study team will liaise with the LSHTM and NIHR marketing and communications teams to endure that the results are disseminated to the public via broader media and through the LSHTM Clinical Trials Unit social media links.

If the intervention is proven effective, research findings will also be presented to potential implementing organisations in the UK including Public Health England and the chlamydia screening programme. Dr Free is an advisor to a number of WHO m-health working groups and will ensure the results are disseminated to WHO and other organisations which support the implementation of effective health interventions internationally.

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

18/12/2018: The following changes were made: 1. The planned sample size was changed from 5000 to 6250. 2. The recruitment end date was changed from 30/03/2018 to 27/11/2018. 3. The overall trial end date was changed from 31/07/2019 to 30/04/2020. 4. The intention to publish date was changed from 31/07/2020 to 01/10/2020. 5. The plain English summary was updated. 10/08/2016: The study contact has been changed from Rebecca Matthews to Rosemary Knight. 05/08/2016: Study status verified with principal investigator.