The effectiveness and cost-effectiveness of behavioural interventions for the prevention of sexually transmitted infections in young people aged 13-19: a systematic review and economic evaluation.

OBJECTIVES To assess the effectiveness and cost-effectiveness of schools-based skills-building behavioural interventions to encourage young people to adopt and maintain safer sexual behaviour and to prevent them from acquiring sexually transmitted infections (STIs). DATA SOURCES Electronic bibliographic databases (e.g. MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, CINAHL, PsycINFO, CCRCT, NHS EED and DARE) were searched for the period 1985 to March 2008. Bibliographies of systematic reviews and related papers were screened and experts contacted to identify additional published and unpublished references. REVIEW METHODS A systematic review of effectiveness and economic evaluation of cost-effectiveness were carried out. A descriptive map of studies that met inclusion criteria was produced, and keywords were developed and systematically applied to these studies to identify a policy-relevant subset of studies for the systematic review. Outcome data for variables including sexual behaviour were extracted. An economic model was developed to compare the costs and consequences of the behavioural interventions. A Bernoulli statistical model was constructed to describe the probability of STI infection. RESULTS There were few significant differences between the interventions and comparators in terms of changes in sexual behaviour outcomes, although there were some significant differences for knowledge and some measures of self-efficacy. The studies included in this review conducted relatively short follow-up assessments at a time when many young people were becoming sexually active. It is therefore possible that favourable behaviour change may have occurred, and become more cost-effective, with time, as sexual activity becomes more routine in young people's lives. The quality of the intervention provider influenced whether or not young people found the interventions to be acceptable and engaging; enthusiasm and considerable expertise were important for effective class management and delivery of skills-building activities, and a supportive school culture was also helpful. Recognition of young people's individual needs in relation to sexual health was another important factor. No conclusions could be drawn on the impact of the interventions on sexual health inequalities due to a lack of relevant data on socioeconomic status, gender and ethnicity. The results of the economic evaluation were considered to be illustrative, mainly due to the uncertainty of the effect of intervention on behavioural outcomes. The results were most sensitive to changes in parameter values for the intervention effect, the transmission probability of STIs and the number of sexual partners. The costs of teacher-led and peer-led behavioural interventions, based on the resources estimated from the relevant randomised controlled trials in our systematic review, were 4.30 pounds and 15 pounds per pupil, respectively. Teacher-led interventions were more cost-effective than peer-led interventions due to the less frequent need for training. The incremental cost-effectiveness of the teacher-led and peer-led interventions was 20,223 pounds and 80,782 pounds per quality-adjusted life-year gained, respectively. An analysis of individual parameters revealed that future research funding should focus on assessing the intervention effect for condom use from a school-based intervention. CONCLUSIONS School-based behavioural interventions for the prevention of STIs in young people can bring about improvements in knowledge and increased self-efficacy, but the interventions did not significantly influence sexual risk-taking behaviour or infection rates. Future investigation should include long-term follow-up to assess the extent to which safer sexual behaviour is adopted and maintained into adulthood, and prospective cohort studies are needed to look at the parameters that describe the transmission of STIs between partners. Funding should focus on the effectiveness of the interventions on influencing behaviour.