Are cross-border county and regional district life expectancy estimates from the Pacific Northwest comparable? A pilot study
Health related states and events do not occur in isolation. Rather, they are dependent on the social, cultural, structural, and historical contexts in which they occur. For instance, Kramer and colleagues (2017) recently showed that age-adjusted, county-specific heart disease mortality in the Southern United States (US) is strongly linked to the county-level prevalence of slave labor in the Antebellum period, which itself is a product of the region’s climate and soil composition. Similarly, Viazie and colleagues (2014) report that Indigenous peoples in North America experience higher heart disease mortality compared to Whites, with the exception of those living in the Southwestern US. Research from Arthur and Diamond (2011) suggest that the health status of the Navajo Nation, relative to other Indigenous people in North America, may be linked to the arid and dry climate, which was unattractive to European colonizers in their search for lush farmlands and rush for Gold ore. In other words, the geographic context which defines the American Southwest may have played to the relative advantage of Navajo health.
Yet, Gallup, Gavieria, and Lora (2003) have demonstrated through case studies in Latin America, that “while geography matters, it need not determine a country’s destiny.” In North America, support for this claim can be demonstrated through analyses of health outcomes in the Pacific Northwest (PNW). The PNW, sometimes colloquially described as the “Cascadia Corridor”, is a geographic and cultural region located in Southwestern Canada and the American Northwest. However, negotiations between the US and Britain in the mid-1800’s led to the imposition of a boundary dividing the Indigenous lands between the two countries. Thereto, the region was jointly occupied as settlers and commercial interest tightened their claim on Indigenous lands. Naturally, strong cross-border relations have continued and recent reports have described “Cascadia” as one of three transnational megaregions in North America (the other two being the Great Lakes Region and Southern California/Tijuana, Mexico). Despite region homogeneity of the PNW, the effect of the US-Canadian Border on population health cannot be ignored.
According to the United States (US) Center for Disease Control and Prevention (CDC), the US is facing an unprecedented increase in mortality,13 while Canadian’s have continued to experience modest improvements in mortality. This trend, as measured by life expectancy at birth (LEAB), contravenes nearly a half century of gains observed across North America. At the national level, the United States and Canada had almost the same LEAB in 1955, but by 1998 Canadians had gained nearly 2.1 years over and above that gained by Americans. In fact, there is now a substantive literature base exploring differences in LEAB between Canada and the US. A likely contributor to the differences in American and Canadian life expectancy include the different approaches in public health and social policy.
However, there are also significant regional differences within-country: At the county level, Southern counties from Oklahoma to West Virginia have seen little increase in life expectancy since the 1980’s. Meanwhile coastal areas have enjoyed higher than average increases in LEAB. These regional differences – and the nuanced social, cultural, structural, historical, and demographic variations associated therewith – have the potential to obscure the effect of public health policies and interventions of interest to cross-country comparisons of life expectancy. Thus, it is important to reduce heterogeneity by studying regions where potentially salient geographic differences are otherwise minimized.
Of course, cross-country comparisons also introduce complications associated with the selection and comparability of geographic analytic units. With this consideration in mind, this pilot study aims to describe LEAB at the regional district (county-equivalents) and county levels in Oregon (OR), Washington (WA), and British Columbia (BC).