Read the rest of this series of blogs about designing and planning population based systems of care here.

Step 2: Defining the Population

Having defined the scope of the system, what is to be included and what is to be left out, the second step is to define the population to be covered and served by the service.

It is essential to define the population to be served precisely, and even when the system is related to a particular bureaucratic entity like a CCG the population needs to be specified in terms of the practice and local authority populations that will be covered. For example, in the paper launching the design of a system for frail elderly people in Oxfordshire by the PCT/CCG this precondition was emphasised as follows—the limits of the population called “Oxfordshire” will need to be defined. In addition localities will need definition.

The population of the CCG seems an obvious population to use in system design, but there are a number of weaknesses or constraints which need to be taken into account if a population based system with a focus on patients and populations, not organisations, is to be designed—for example:

• The population size of the average CCG is too small for a system for many conditions; even the biggest CCG may not have an adequate population size for some major health problems, such as epilepsy or inflammatory bowel disease.
• The geographical configuration of many CCGs does not reflect long standing communities of practice across networks of expertise and neither the geographical configuration of many local authorities; there may be two or more CCG’s within a large higher tier authority and patients often cross local authority or CCG  boundaries.

For example, in England there are, and have been for many years, only twelve populations for end stage renal failure and only four for neurofibromatosis so it is essential to agree the right population size for a system taking into account:

• The prevalence of a condition.
• The need for  specialist or super specialist skill.
• The need for capital investment.

Patient access is also a consideration, but the creation of a small number of systems and networks does not necessarily mean that all patients have to travel to one place because, by definition, these are knowledge based organisations and knowledge can be mobilised to be where it is needed, including the patient’s own home.

Muir Gray is visiting professor of knowledge management, Nuffield Department of Surgery, University of Oxford.