Unpacking income inequality and population health: the peculiar absence of geography.

BACKGROUND A large and growing body of literature investigating the negative relationship between income inequality and population health (at different geographic scales) has developed over the past several years, although the relationship is not universal apparently. We argue that there has been a peculiar absence of geography in studies of the relationship between income inequality and population health and that explanations for the mixed results have been hampered by an inattention to geography. METHODS Using methods of spatial pattern visualization, outlier analysis and comparative case study analysis, we investigate the role of "geography" as a means of "unpacking" the relationship between income inequality and health in Canada and the United States. RESULTS The findings demonstrate how analyzing the study of income inequality and population health in the context of place makes otherwise obscure patterns visible and opens up new questions and opportunities for investigating how unequal places may be less healthy than more egalitarian ones. Rather than dismissing the importance of income inequality and health because it does not appear to exist at all times and in all places, we raise questions such as: Under what conditions does the relationship between income inequality and population health hold? and What, if anything, is similar about places where it does (or does not) hold? as crucial questions requiring a different kind of analysis than has been common in this literature. CONCLUSION We recommend that place and health studies seek this balance between universalistic and particularistic explanations of place and health relationships in order to best understand the socio-geographic production of health.