Distribution of sexual health knowledge and attitudes in adolescent social networks: social network analysis of data from the STIs and Sexual Health feasibility study

Abstract Background The social patterning of important precursors to sexual behaviour could help inform the potential reach of social network interventions. We aimed to investigate how peer networks might influence diffusion of sexual health messages in the context of a school-based peer-led sexual health intervention. Methods We used data from the control arm of the STIs And Sexual Health (STASH) study, an ongoing cross-sectional survey of Scottish secondary school pupils (4th year, age 14–16 years), to measure sexual health knowledge, attitudes, confidence, and sexual experience. We constructed social networks using questions about friends within the school year. There were 696 respondents from 864 enrolled pupils (response rate 81%, 346 [50%] boys), recruited from six schools. There were no power calculations for this feasibility study. Exponential random graph models were used to assess whether the log odds of two individuals having a friendship tie varied according to similarity between individuals on key characteristics. Random-effects meta-analysis combined preliminary results across six schools. The University of Glasgow Medicine Veterinary and Life Sciences Ethics committee approved the study, and participants gave informed consent online before completing the survey. Findings There was some evidence that friendship ties were more common among those with similar knowledge (difference coefficient −0·01, 95% CI −0·04 to 0·01) and attitudes (−0·02, −0·04 to 0·00), but not confidence (0·30, −0·31 to 0·91), with considerable heterogeneity between schools ( I 2 knowledge 27%, attitudes 2%, confidence 100%). A negative difference coefficient means that two pupils with different levels of knowledge or attitudes are less likely to have a friendship tie than those with the same level. Ties were more common among those with similar sexual experience: two pupils who were both sexually active had 0·35 greater log odds of a friendship tie than did a sexually active and not active pupil pair (95% CI 0·21 to 0·50, I 2 =23%). Interpretation Our finding that adolescent school friendships cluster according to sexual experience, knowledge, and attitudes strengthens the evidence-base for peer-led sexual health interventions using social diffusion approaches. Funding None.