Sexual network position and risk of sexually transmitted infections

A population-based sexual network study was used to identify sexual network structures associated with sexually transmitted infection (STI) risk, and to evaluate the degree to which the use of network-level data furthers the understanding of STI risk.

Participants (n = 655) were from the baseline and 12-month follow-up waves of a 2001-2 population-based longitudinal study of sexual networks among urban African-American adolescents. Sexual network position was characterised as the interaction between degree (number of partners) and two-reach centrality (number of partners' partners), resulting in the following five positions: confirmed dyad, unconfirmed dyad, periphery of non-dyadic component, centre of star-like component and interior of non-star component. STI risk was measured as laboratory-confirmed infection with gonorrhoea and/or chlamydia.

Results of logistic regression models with generalised estimating equations showed that being in the centre of a sexual network component increased the odds of infection at least sixfold compared with being in a confirmed dyad. Individuals on the periphery of non-dyadic components were nearly five times more likely to be infected than individuals in confirmed dyads, despite having only one partner. Measuring network position using only individual-based information led to twofold underestimates of the associations between STI risk and network position.

These results demonstrate the importance of measuring sexual network structure using network data to fully capture the probability of exposure to an infected partner.