Table 2.

Examples of catchment models of general practice in different countries

Model	Definition	Health example
Two Step Floating Catchment Area method. (and enhanced 2SFCA method) (2000, 2003, 2009) USA.	A special case of the gravity model, using a special form of the physician to population ratio. The enhanced 2SFCA method addresses the problem of uniform access within the catchment by applying weights to different travel time zones to account for distance decay.	It measures spatial accessibility to primary care physicians.
		It reveals spatial accessibility patterns more consistent with intuition, and delineates explicit health professional shortage areas.
Synthetic Data Matrix (SDM, 2005) Northern Ireland data.	Compares patient to GP flow (affiliation) information aggregated at the Census Enumeration District level across a number of catchment areas using different methodologies. The SDM is then analysed using a modified version of the European Regionalisation Algorithm to create an optimal set of non overlapping regions according to predefined population size and self-containment criteria.	General practices within a defined health region.
Practice Health Atlas method. (PHA, 2006, 2010) Australia.	Provides catchment maps of patients of individual general practices, based on post code place of residence. Maps patient catchments in 7 chronic disease categories. Details level of utilisation of health services and documents level of health outcomes for specific disease groups. Describes the general practice market share of each individual postcode within a region.	General practices within a defined health region. The PHA has the capability to measure individual catchments or aggregated catchments at city or regional level.
Local Potential Accessibility (LPA) measure. (2012) France.	The LPA indicator measures the supply and demand for general practice services by taking into account practitioners’ volume of activity on the one hand, and service use rates differentiated by population age structure on the other.	The LPA indicator to private GPs indicator reveals a greater degree of variability than the traditionally used accessibility indicators (travel time, level of GP density in living areas …)
Lewis & Longley Model (2012) England.	An analysis of a data set, derived from the National Health Service Central Register. The Model compares the observed patient registrations at GP surgeries with an optimum geographic pattern.	From the London borough of Southwark. The has a focus on spatial equity of access.
	The Model also uses a new ethnicity classification tool to assess the ethnic dimensions to deviations from the normative arrangement.	The Model maps the role of the GP surgery as a place that provides local services in away that tries to serve the population as a whole (spatial equity).