Young people are the group most affected by acute sexually transmitted infections (STIs) such as chlamydia. In 2023, over 40% of the 401,800 diagnoses made in England were among those aged 15–24 years.1 We know that the risk of STIs among young people is unequal. Diagnoses are higher among those who identify as black; live in areas of higher deprivation; and are gay, bisexual or identify as men who have sex with men (GBMSM).1 Untreated STIs can lead to serious consequences such as pelvic inflammatory disease, ectopic pregnancy, infertility, stillbirth and increased risk of human immunodeficiency virus (HIV).2 They have a significant impact on the quality of life and are associated with stigma, which can impact the willingness to seek care and contribute to onward spread.2 Condoms are recommended for the prevention of STIs,1 but young people report inconsistent use.3 The National Institute for Health and Care Excellence (NICE) recommends that a range of settings are provided for STI testing, including web-based.4 Web-based STI testing involves visiting a website to request a STI self-sampling kit (often free in the UK to under-25s). Kits are posted to users, allowing them to take a sample and return it to a laboratory for testing. Text messages communicate negative results and direct those with positive results to local services for treatment. Against a backdrop of rising demand for sexual health services, sustained budget cuts, and changes to service delivery resulting from the coronavirus disease discovered in 2019 (COVID-19) pandemic, there has been a rapid growth in the use of web-based STI-testing services over the last 5 years.5 This is reflected in the National Chlamydia Screening Programme (NCSP) data, which show increases in use among 15- to 24-year-olds since 2017, rising to 43% of all testing in 2023.1
Evidence indicates that STI self-sampling websites are as effective as in-person services at reaching groups experiencing higher STI diagnosis rates; chlamydia positivity is comparable to that of other non-specialist services (which include sexual and reproductive health services, young people’s services, and other outreach or community-based settings),1 and they attract equivalent numbers of young people who identify as GBMSM and of black ethnicity compared to other in-person services combined.6 Repeated use of internet testing services is however common, with chlamydia positivity remaining high for those that retest,7 suggesting that testing online does not reliably translate into future individual prevention efforts. National STI management standards state that all people accessing STI testing should be provided with health promotion and prevention interventions, including encouragement of safer sex behaviour and condom use.8 Most STI-testing websites do not however comply with this guidance.9 Given the continued growth of the web-based STI-testing sector, this presents an important and currently missed opportunity to reduce the sexual health inequality experienced by young people through timely intervention.
The Wrapped intervention aims to support young people to use condoms correctly every time they have penetrative sex. It was co-created by researchers, health professionals and young people in 2016–17 with support from Medical Research Council (MRC) Public Health Intervention Development (PHIND) funding. Wrapped is a multicomponent and interactive digital intervention developed especially for users of web-based STI-testing services aged 16–24 years. Users’ initial interaction is through selection of their salient barriers to condom use. These barriers reflect important behavioural determinants of condom use identified through existing meta-analyses,10–13 namely condom-use attitudes (particularly beliefs around pleasure, enjoyment and spontaneity), condom availability, and self-efficacy for condom use and communication. Responses determine which combination of up to six different components they receive. Users therefore only receive components for which there is an expressed need, a strategy selected to optimise user engagement and cost-effectiveness.
Scores of behavioural interventions aiming to reduce sexual risk behaviour have been developed over recent decades. What this body of work tells us is that behavioural interventions have modest favourable effects on condom use and STI incidence, including for different populations and when delivered via face-to-face or digital methods.14,15 There are a number of important qualifications to be made to this statement, however. A minority of studies examining the effect of these interventions use the most defensible design, that is, a randomised controlled trial (RCT).16,17 This is important because other types of design have a tendency to overestimate effects and are not informative regarding causality. Furthermore, when RCTs are conducted they are often of poor quality. A meta-analysis of RCTs by Free et al.,16 for example, included 139 trials of which only 4 were judged as scoring adequately on all four quality criteria (allocation sequence, allocation concealment, loss to follow-up and blinding of outcome assessment). Biological outcome measures are also rare; for example, only 15% of studies in the Free et al. review16 and 13% of studies in a meta-analysis of interactive computer-based interventions by Bailey et al.17 were found to have used this type of measure. The length of follow-up for the primary outcome is also typically limited. In the meta-analysis by Bailey et al.,17 for example, 5 of the 15 studies had a follow-up of < 2 weeks post intervention and the longest follow-up period was 6 months, achieved by only two studies. This limits conclusions that can be drawn about the long-term benefits of interventions on sexual health outcomes. In sum, despite the volume of work in this area, well-designed, high-quality trials are urgently required to provide reliable evidence on the effect of behaviour change interventions on sexual health outcomes. This is true for all types of interventions, including those delivered via digital methods.
Wrapped is now ready to be definitively tested using a RCT to determine its cost-effectiveness. To respond to previous criticisms of trials in this area and contribute reliable evidence concerning the effect of behaviour change interventions on sexual health outcomes, it is imperative that this future RCT uses procedures that minimise bias, has a long-term follow-up, and includes an objective, biological outcome. Because RCTs are complex and expensive, it was necessary to first run a feasibility randomised controlled trial (fRCT) to assess whether and how it might be possible to carry out this definitive trial.
In Chapter 2 which follows, we describe the development of a recruitment and retention strategy to guide a future definitive trial. In Chapter 3, we describe a fRCT of Wrapped. Primary outcomes for judging the success of this fRCT were recruitment rate and completeness of chlamydia self-sampling test data at final follow-up. In Chapter 4, we describe our health economic assessment. In Chapter 5, we describe qualitative interviews to explore participants’ experiences of the trial and their views and experiences of the intervention. In Chapter 6, we present our assessment of potential pathways for future implementation of Wrapped. Finally, in Chapter 7, we summarise the principal findings, the contribution of the work to existing evidence, the study strengths and limitations, and make recommendations for future research.