IJE Advance Access originally published online on February 28, 2006
International Journal of Epidemiology 2006 35(3):623-632; doi:10.1093/ije/dyl026
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Article |
Peripherality, income inequality, and life expectancy: revisiting the income inequality hypothesis
1 Centre de recherche de Centre Hôpital de Université de Montréal, 3875 St Urbain, Montréal, QC, Canada H2W 1V1
2 Centre for Health and Policy Studies, Department of Community Health Sciences, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4T1
* Corresponding author. Spencer Moore, PhD, MPH, Centre de recherche du CHUM, Axe santé des populations et épidémiologie sociale, 3875 St Urbain, 3e étage, porte 3-30, Montréal, QC, Canada H2W 1V1. E-mail: spencer.moore{at}umontreal.ca
Background Recent criticisms of the income inequality and health hypothesis have stressed the lack of consistent significant evidence for the stronger effects of income inequality among rich countries. Despite such criticisms, little attention has been devoted to the income-based criteria underlying the stratification of countries into rich/poor groups and whether trade patterns and world-system role provide an alternative means of stratifying groups.
Methods To compare income-based and trade-based criteria, 107 countries were grouped into four typologies: (I) high/low income, (II) OECD membership/non-membership, (III) core/non-core, and (IV) non-periphery/periphery. Each typology was tested separately for significant differences in the effects of income inequality between groups. Separate group comparison tests and regression analyses were conducted for each typology using Rodgers (1979) specification of income, income inequality, and life expectancy. Interaction terms were introduced into Rodgers specification to test whether group classification moderated the effects of income inequality on health.
Results Results show that the effects of income inequality are stronger in the periphery than non-periphery (IV) (–0.76 vs –0.23; P < 0.05). An incremental F-test confirmed significant differences in the coefficient subsets between the two groups (F2,101 = 6.31; P < 0.01).
Conclusions Cross-national analyses of income inequality and population health have assumed (i) income differences between countries best capture global stratification and (ii) the negative effects of income inequality are stronger in high-income countries. However, present findings emphasize (i) the importance of measuring global stratification according to trading patterns and (ii) the strong, negative effects of income inequality on life expectancy among peripheral populations.
Keywords Trade, income inequality, global health, life expectancy
Accepted 31 January 2006