Using simulation modelling to assess service viability in Nottinghamshire

Work began in Bassetlaw, with a project focussing on the specific situation of that part of the county, and sparked in particular by local discussions about the role of the local inpatient unit in Worksop.

The rest of the CCGs in Nottinghamshire subsequently agreed to join a county-wide project, considering both specific issues of relevance to those parts of the county – but also, crucially, the cross-county situation, particularly for resources which are used by communities across the county.

In practice, a wide range of specific questions and scenarios emerged as the project progressed, some directly related to the original questions, and some developing from these discussions.

The project focussed on services for adults of all ages provided by the Nottinghamshire Healthcare NHS Foundation Trust only.

The technique applied was discrete event simulation modelling. This approach required construction of a statistical model of the current operation of services, identification of scenarios for change, and interactive modelling of the effects of those scenarios to achieve the optimum use of resources. This is based, not on use of simple averages and standardised flows, but on the creation of patient cohorts and presentations which mimic, as far as possible, the variance between patients and patient events which happens in real life.

Our modelling suggested that, over the five year modelling period, without mitigation measures, current bed numbers are likely to be insufficient. Our estimate is that a total bed pool of 170 working age adult beds, 63 organic, and 65 functional for older people could be required by the end of that period, based on current service trends, and demographic change.

However, if the following measures could be implemented, as analysed above:

  • establishment of crisis cafes in each of Newark, Mansfield, and Nottingham
  • expansion of home treatment teams
  • implementation (as planned) of 12 step-down beds
  • some retained use of leave beds (only up to half of pre-discharge leave, on average)

the requirement could fall to perhaps 141 adult acute beds, 54 organic, and 51 functional illness for older people.

There therefore appears to be the risk of a gap between capacity and demand approximating to 17 adult acute beds, and 15 beds for older people. The older people’s “beds” could be addressed by an increase in the capacity of intensive support teams for older people, where there is good confidence that there remain older people using inpatient services at present, who could be managed via community intensive support, if such services existed.

The adult acute gap is more difficult to fill. We considered in detail the numbers of “divertable” people, and we made significant assumptions about the potential opportunities for diversion. We did not suggest that additional beds be immediately planned; clearly the next step needs to be establishment of additional community-based alternatives, and careful evaluation of their impact. If this proves more successful than currently hoped, it may be that the existing bed base will prove sufficient.

"Thanks again for the excellent work on the modelling and the project report. Incredibly helpful. Great how you separated out the demographic change, and identified where demand has increased over the last 3 years."

Simon Castle – Asst Director of Commissioning – Nottingham City CCG