Interpreting the results of a modified gravity model: examining access to primary health care physicians in five Canadian provinces and territories

Abstract

Background: Primary health care (PHC) encompasses an array of health and social services that focus on preventative, diagnostic, and basic care measures to maintain wellbeing and address illnesses. In Canada, PHC involves the provision of first-contact health care services by providers such as family physicians and general practitioners - collectively referred as PHC physicians here. Ensuring access is a key requirement of effective PHC delivery. This is because having access to PHC has been shown to positively impact a number of health outcomes.

Methods: We build on recent innovations in measuring potential spatial access to PHC physicians using geographic information systems (GIS) by running and then interpreting the findings of a modified gravity model. Elsewhere we have introduced the protocol for this model. In this article we run it for five selected Canadian provinces and territories. Our objectives are to present the results of the modified gravity model in order to: (1) understand how potential spatial access to PHC physicians can be interpreted in these Canadian jurisdictions, and (2) provide guidance regarding how findings of the modified gravity model should be interpreted in other analyses.

Results: Regarding the first objective, two distinct spatial patterns emerge regarding potential spatial access to PHC physicians in the five selected Canadian provinces: (1) a clear north-south pattern, where southern areas have greater potential spatial access than northern areas; and (2) while gradients of potential spatial access exist in and around urban areas, access outside of densely-to-moderately populated areas is fairly binary. Regarding the second objective, we identify three principles that others can use to interpret the findings of the modified gravity model when used in other research contexts.

Conclusions: Future applications of the modified gravity model are needed in order to refine the recommendations we provide on interpreting its results. It is important that studies are undertaken that can help administrators, policy-makers, researchers, and others with characterizing the state of access to PHC, including potential spatial access. We encourage further research to be done using GIS in order to offer new, spatial perspectives on issues of access to health services given the increased recognition that the place-based nature of health services can benefit from the use of the capabilities of GIS to enhance the role that visualization plays in decision-making.

Figure 1

Provinces and territories of focus. This map displays the five provinces and territories that are examined in the present article.

Figure 2

Potential spatial primary health care physician access in Newfoundland and Labrador. Potential spatial access to primary health care physicians in Newfoundland and Labrador. Whilst the most populated areas enjoy varying degrees of access, remote areas are generally lacking services.

Figure 3

Potential spatial primary health care physician access in Nunavut. Potential spatial access to primary health care physicians in Nunavut. Here access is excellent within the two most populated cities and missing entirely outside the borders where the roads end.

Figure 4

Potential spatial primary health care physician access in Ontario. Potential spatial access to primary health care physicians in Ontario. Ontario is Canada’s most populated province. Here there is a distinct north–south pattern of access.

Figure 5

Potential spatial primary health care physician access in British Columbia. Potential spatial access to primary health care physician in British Columbia. Inequities of access exist across the province. Here dramatic topography affects both provision of health services and access to them.

Figure 6

Potential spatial primary health care physician access in Nova Scotia. Potential spatial access to primary health care physicians in Nova Scotia. The modified gravity model results show relatively uniform access across the small and lightly populated province.