How Status Quo Bias Shapes Willingness, Uptake, and Adherence to PrEP Among Chinese MSM: A Behavioral Economics Perspective

INTRODUCTION: Implementing pre-exposure prophylaxis (PrEP) is hindered by a significant "PrEP Cliff", a sharp decline from willingness to uptake and adherence. This study aimed to integrate status quo bias theory with a dual-process model, seeking to understand how this bias influences the PrEP cascade among men who have sex with men (MSM) in China. METHODS: A cross-sectional survey was conducted among 1022 MSM across six provinces in China from November 2024 to February 2025. Through regression models, we tested a moderated mediation framework to examine how status quo bias influenced PrEP willingness, uptake, and adherence, focusing on the mediating role of PrEP resistance intention and the moderating role of condom-use inertia. RESULTS: Participants were generally young (≤ 30 years; 63.1%), mostly unmarried (88.5%), and well-educated (89% with a bachelor's degree or higher). The "PrEP Cliff" was evident, characterized by high awareness (91.3%) and willingness among non-users (58.9%), but low uptake (46.2%) and poor adherence, with 53.4% of users self-reporting lower adherence. In the initiation phase (willingness and uptake), PrEP resistance intention significantly mediated the associations of transition costs and social norms on PrEP cascade outcomes. Condom-use inertia significantly moderated this mediation pathway by strengthening the associations of transition costs (β = 0.06, 95% CI 0.01 to 0.11) and social norms (β = - 0.05, 95% CI - 0.10 to 0.00) on PrEP resistance intention. However, the mechanism shifted during the adherence phase. Adherence was instead predominantly predicted by the direct associations of transition costs (β = - 0.44, 95% CI - 0.64 to - 0.23) and social norms (β = 0.56, 95% CI 0.38 to 0.74). CONCLUSION: This study provides an evidence-based framework for clinicians and public health programs to design stage-specific interventions tailored to the distinct psychological barriers that dominate each phase.