Estimating catchment populations in the South West: why and how

The concept of a ‘catchment areas’ and ‘catchment populations’ relate to the study of the geographical and demographic distribution of a health care service. A catchment population is the number of people resident in the catchment area who are (or who are at risk of being) patients of the NHS hospital trust. These data can be used for planning services but also have the potential to inform the understanding of patterns of health inequality and the equitable provision of services. This paper presents the method and results of a project by the South West Public Health Observatory estimating catchment populations for Trusts in the South West region of England. The method utilises Census area statistics wards, Hospital Episodes Statistics and resident population estimates and uses the Norris-Bailey proportionate flow method. Tables of catchment populations and maps of catchment areas will be presented, and the demographic characteristics of Trust populations will be compared. In discussing our methods and results we will seek feedback on our chosen methodology and on the usefulness of additionally calculating catchment populations and areas for particular categories and causes of admission.