Online Social Interaction, Neighborhood Perception, and the Mediating Role of Social Capital in Charitable Giving for Seriously Ill Patients: Cross-Sectional Study

Background: Online public welfare and donation-based crowdfunding have rapidly expanded, motivating individuals to engage in charitable giving through digital platforms. However, the influence of online social interactions and offline neighborhood perceptions on donation behavior remains underexplored. Objective: This study investigates how online social interactions influence individuals' intentions to donate to patients with serious illness, focusing on the mediating roles of bridging and bonding social capital and the moderating effect of neighborhood perception. It integrates online and offline social contexts to explain donation behavior. Methods: Data were collected from individuals recruited through the "3C" (Caring for Children with Cancer) Health Care Volunteer Community in Guizhou, China. Validated scales were used to measure online social interaction, social capital, donation intention, and neighborhood perception. A total of 450 valid responses were obtained between August and October 2023, with a 91.46% response rate. Results: Online social interaction was positively associated with donation intention (β=0.37, P<.01). It significantly predicted both bridging social capital (β=0.45, P<.01) and bonding social capital (β=0.54, P<.01), which in turn were positively associated with donation intention (β=0.48 and β=0.54, respectively, P<.01). Bridging social capital partially mediated this relationship, whereas bonding social capital showed a stronger mediating effect. Neighborhood perception significantly moderated the relationship between online social interaction and both bridging (β=0.17, P<.01) and bonding social capital (β=0.18, P<.01). Furthermore, moderated mediation analysis showed that the indirect effects were stronger at higher levels of neighborhood perception (bridging: β=0.278; bonding: β=0.340) than at lower levels (bridging: β=0.150; bonding: β=0.181). The indices of moderated mediation were significant for both bridging (β=0.080, 95% CI 0.021-0.142) and bonding social capital (β=0.100, 95% CI 0.040-0.162). Conclusions: Online social interaction was associated with increased donation intentions to patients with serious illness via bridging and bonding social capital, with bonding ties fully and bridging ties partially mediating the effect. Neighborhood perception strengthened these pathways, indicating that offline social context can amplify the impact of online engagement on charitable giving. These findings highlight the importance of integrating digital interaction and offline social context in promoting health-related charitable giving.