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 May 2020
Who is funding the study?
National Institute for Health Research (UK)
Who is the main contact?
Main contact as of 18/12/2018:
Previous main contact:
Miss Rebecca Matthews
Ms Kimberley Potter
Clinical Trials Unit (CTU)
Department of Medical Statistics
London School of Hygiene and Tropical Medicine
+44 207 7927 2473
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
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.
London - Riverside Research Ethics Committee, 16/10/2015, ref: 15/LO/1665
Randomised controlled trial
Primary study design
Secondary study design
Randomised controlled trial
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
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
Current secondary outcome measures as of 30/10/2019:
Measured at 4 weeks:
1. Whether participants took the (prescribed antibiotic) treatment and avoided sex for 7 days after treatment, self-reported on 4-week questionnaire
2. Whether they told the last person they had sex with before testing positive, that they needed to get treatment, self-reported on 4-week questionnaire
3. Clinic attendance by partner for treatment, identified from clinic records
4. Condom use at last sex, self-reported on 4-week questionnaire
Process outcomes – scores of the theoretical constructs underlying the components of the intervention (behaviour change mediators):
1. Attitudes towards partner notification, self-reported on 4-week questionnaire
2. Self–efficacy in telling a partner about an infection, self-reported on 4-week questionnaire
3. Self–efficacy in negotiating condom use, self-reported on 4-week questionnaire
4. Correct condom use self-efficacy, self-reported on 4-week questionnaire
5. Knowledge related to STIs, self-reported on 4-week questionnaire
Measured at 1 year:
1. Diagnosed with any STI after joining the trial according to self-report confirmed by postal test results and clinic records, self-reported on 1-year questionnaire
1. Condom use at last sex, self-reported on one year questionnaire
2. Number of sexual partners since joining the trial, self-reported on one year questionnaire
3. Sex with someone new since joining the trial, self-reported on one year questionnaire
4. Condom use at first sex with most recent new partner, self-reported on one year questionnaire
5. Self-reported sexually transmitted infection testing for self - prior to first sex with most recent new partner, self-reported on 1-year questionnaire
6. Sexually transmitted infection testing for self - prior to first sex with most recent new partner, confirmed according to clinic record that testing occurred
7. Participant’s report as to whether their most recent new partner was tested for sexually transmitted infection prior to sex with them, self-reported on 1-year questionnaire
8. Number of sexual partners since joining the trial, self-reported on 1-year questionnaire
9. Reading and sharing of intervention content, self-reported on 1-year questionnaire
10. Number of text messages read, self-reported on one year questionnaire
11. Whether anyone else read the messages, if yes how did the participant feel about them reading the messages? Self-reported on 1-year questionnaire
12. Reading someone else’s messages in the trial (to be reported for control group participants), self-reported on 1-year questionnaire
13. Someone else in the trial reading participants’ messages (to be reported for intervention group participants), self-reported on 1-year questionnaire
1. Car accident where the participant was the driver in the past year, self-reported on one year questionnaire
2. Experience of partner violence in the past year, self-reported on one year questionnaire
Previous secondary outcome measures:
1. Clinic attendance by partner for treatment is determined at 4 weeks
2. Whether participants took the treatment and avoided sex for 7 days after treatment is determined at 4 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
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
Trial participating centre
London School of Hygiene and Tropical Medicine
National Institute for Health Research
Funding Body Type
Funding Body Subtype
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)
2020 protocol in https://www.ncbi.nlm.nih.gov/pubmed/32152156 (added 11/03/2020)
- ISRCTN64390461_SAP_v6_10June2020.pdf Uploaded 19/06/2020