With thanks to Professor Christos Vasilakis – pictured top – (Founding Director of the Centre for Healthcare Innovation and Improvement – CHI²) and Dr. Zehra Onen Dumlu at the University of Bath – pictured below – for contributing this insight…
Delays in hospital discharge—often referred to as ‘bed blocking’—remain one of the most pressing operational issues facing NHS hospitals. NHS England figures from February 2024 show that between 13,200 and 14,200 patients were occupying beds each day despite being medically fit to leave. That’s more than one in eight general and acute beds unavailable for new admissions.
These delays are usually caused by difficulties arranging follow-on care, such as community nursing or social support. The wider impact is substantial, creating bottlenecks across the system, reducing hospital capacity, and negatively affecting patient flow and experience.
To address this, the Improving Patient Flow between Acute, Community, and Social Care (IPACS) project was launched in 2020, funded by Health Data Research UK. It brought together researchers from the University of Bath and University of Exeter Medical School, alongside operational leaders from the Bristol, North Somerset and South Gloucestershire (BNSSG) Integrated Care Board (ICB).
The IPACS team developed an open-source simulation model to help NHS decision-makers analyse the complex dynamics of patient flow and discharge. The model is grounded in Operational Research (OR), using advanced analytical techniques to solve real-world problems. Its purpose: support better planning, evaluate service changes, and improve discharge efficiency.
Led by Professor Christos Vasilakis and Dr. Zehra Onen Dumlu at Bath, alongside Professor Martin Pitt and Dr. Alison Harper in Exeter, the team worked closely with NHS partners including Dr. Richard Wood and Dr. Paul Forte to ensure real-world relevance.
A major focus was the ‘Discharge to Assess’ (D2A) service, which helps move patients from hospital to community settings. The team modelled three D2A pathways:
Using real data from the BNSSG region—home to one million residents—the model simulated how patients moved through these pathways, testing different scenarios to assess how changes in capacity or processes could reduce delays.
Built using open-source R software, the tool allows NHS teams to run “what if” simulations, analyse demand patterns, and plan resources more effectively.
The model’s outputs have already informed a £13 million business case to enhance local D2A services—demonstrating its practical value. While it doesn’t yet capture every element of discharge (e.g. palliative care, social care inputs), it lays a strong foundation for future development.
Ultimately, IPACS shows how simulation modelling can help the NHS tackle delayed discharge by making smarter, evidence-based decisions—freeing up beds, improving patient care, and making the system more efficient.
