Abstract for: A Hybrid System Dynamics–Discrete Event Simulation Framework to Model Behavioural Demand Self-Regulation in Specialist Healthcare

Long waiting times for specialist consultations remain a major challenge in healthcare systems, particularly in high-demand services such as traumatology. These delays result from complex interactions between demand, referral behaviour, and operational capacity, making it difficult to anticipate the system-wide effects of organisational changes. This study develops a hybrid System Dynamics–Discrete Event Simulation (SD–DES) framework that combines a data-driven digital twin with a behavioural modelling layer. The model represents how patient care-seeking and physician referral decisions evolve in response to perceived system conditions. The framework shows that behavioural responses primarily redistribute demand across entry and referral pathways rather than reducing it. As a result, congestion may shift between system components, generating uneven workload distribution and pathway-dependent performance dynamics. These findings highlight that system performance depends not only on capacity and design, but also on how demand is behaviourally distributed across pathways. Ignoring behavioural adaptation may lead to misleading conclusions when evaluating organisational interventions in healthcare systems.