Generic Hospital Modelling

Adrian Fletcher (2012)

A ‘generic’ model is sometimes seen as a ‘general’ model which can be tailored to reflect local circumstances or as a model of the ‘general’ features of a commonly occurring problem. The UK Department of Health had some success with a model of Accident & Emergency Services which to some extent spanned both these definitions. This research concerns the extrapolation of these ideas to a whole hospital setting. See reference below for description of early A&E model.

Accident and Emergency (A&E) departments deal with emergency patients in NHS acute hospitals in England. They have access to diagnostics facilities and inpatient beds. A previous government target was that 98% of A&E patients should be completed within four hours.

The author was the analytical lead for emergency care in the Department of Health (DH) in 2003 and 2004, responsible for analytical support to ministers on issues faced by the NHS in managing A&E patient flow. A so-called ‘generic’ discrete event simulation model of A&E services was developed at this time. It described a ‘typical’ A&E department and enabled detailed investigation and facilitated workshop discussions of potential interventions. It helped advise whether the target was achievable. The development and use of this model at national level is described. An opportunity is also described to use the model in hospital trusts where it was also found to be useful.

The experiences with this model provided the motivation to investigate this area further. Simulation is widely used to model A&E services, but very few models are ‘generic’ – they are usually designed for specific trusts. Three particular research questions are investigated:

  1. What are generic hospital simulation models?

  2. How can generic hospital simulation models be built?
  3. Can they be useful?

This research uses a literature review and an informal survey of health OR academics and experienced DH modellers to generate two answers to question 1: a broad four level classification of model types, and a more detailed framework of typical characteristics of generic hospital simulation models.

An improved ‘generic’ A&E patient flow simulation model was then developed to address the shortcomings of the first model, particularly through increased scope and detail. Experiences with both the original DH model and this improved model provide answers to the second question in identifying different build techniques and important issues to consider when developing generic models.

The improved model was used with DH on two case studies: possible NHS responses to a potential swine flu pandemic, and the impact of patient mix and resuscitation patients on A&E performance. This experience, and that with the first model, provide answers to the third question by examining the successes and failures of the use of the models at national and hospital trust level. Possible reasons for the relative levels of success are discussed.   


Fletcher A, Halsall D, Huxham S and Worthington D, 2007, ‘The DH Accident and Emergency Department model: a national generic model used locally’, Journal of the Operational Research Society, vol 58, pp1554 – 1562.

Fletcher A and Worthington D, 2009, ‘What is a ‘generic’ hospital model? – A comparison of ‘generic’ and ‘specific’ hospital models of emergency flow patients’, Health Care Management Science, vol 12, Issue 4, pp374-391.