Effectiveness of a Combined Peer and Digital-led Intervention Program for College Students with High-Risk Sexual Behaviors: A Randomized Controlled Trial Based on the Behavior Change Wheel Model

Background Risky sexual behavior (RSB) among college students is a major public health concern, leading to high rates of sexually transmitted infections (STIs) and adverse outcome. Traditional educational interventions often fail to translate knowledge into sustained behavioral change. The Behavior Change Wheel (BCW) theory provides a systematic framework for developing theory-informed interventions. This study aimed to develop and evaluate the effectiveness of a BCW-based intervention, combining peer and digital-lead intervention, to reduce RSB among Chinese college students. Methods A two-phase study was conducted. Phase 1 involved a qualitative study (n = 15) to identify barriers and facilitators to safer sex, a literature review, and a Delphi expert consultation (n = 13) to develop the intervention. Phase 2 was a randomized controlled trial to assess the effectiveness of the intervention. Seventy-six college students with a history of RSB were recruited and randomly assigned to the intervention group (n = 38) and control group (n = 38). The intervention group received a 6-week, peer and digital-lead ("SiLiang Health") intervention, while the control group received routine sexual health education. Primary outcomes were the frequency of RSB and risk perception. Secondary outcomes were psychosexual health and sense of shame related to sexuality. Assessments were conducted at baseline (T0), immediately post-intervention (T1), and one-month post-intervention (T2). Intention-to-treat (ITT) was used and data were analyzed using Generalized Estimating Equations (GEE). Results The analyses revealed significant group-by-time interaction effects on all outcome variables. For the primary outcome of RSB frequency, the intervention group showed a marked decrease from a baseline mean (SD) of 3.42 (1.00) to 2.51 (0.69) at T1 and 1.97 (0.71) at T2, with the reduction being significantly greater than that in the control group (p < 0.01; Cohen's d at T2 = 0.87). Risk perception scores increased significantly in the intervention group from 2.03 (1.37) at baseline to 4.54 (1.30) at T1 and 4.51 (1.44) at T2, with a significant group effect (p < 0.01) and a large effect size (Cohen's d at T1 = -2.20). It also confirmed significant improvements in psychosexual health in the intervention group, with lower scores on the sexual cognition and sexual attitude subscales (p < 0.01), and a pronounced reduction in the sense of shame (p < 0.01), all effect sizes ranging from medium to large. Conclusions BCW theory-based intervention, combining peer-led group sessions and digital support, is effective to reducing RSB and improving sexual health outcomes among college students. This intervention model offers a practical and engaging paradigm for healthcare professionals and educators working in adolescent and young adult health. Trial registration: Clinical registration number: NCT12345678(30/05/2024) .