Socioeconomic determinants of infant mortality:: A worldwide study of 152 low-, middle-, and high-income countries

Background: To reach the Millennium Development Goals for health, influential international bodies advocate for more resources to be directed to the health sector, in particular medical treatment. Yet, health has many determinants beyond the health sector that are less evident than proximate predictors. Aim: To assess the relative importance of major socioeconomic determinants of population health, measured as infant mortality rate (IMR), at country level. Methods: National-level data from 152 countries based on World Development Indicators 2003 were used for multivariate linear regression analyses of five socioeconomic predictors of IMR: public spending on health, GNI/capita, poverty rate, income equality (Gini index), and young female illiteracy rate. Analyses were performed on a global level and stratified for low-, middle-, and high-income countries. Results: In order of importance, GNI/capita, young female illiteracy, and income equality predicted 92% of the variation in national IMR whereas public spending on health and poverty rate were non-significant determinants when adjusted for confounding. In low- income countries, female illiteracy was more important than GNI/capita. Income equality ( Gini index) was an independent predictor of IMR in middle- income countries only. In high-income countries none of these predictors was significant. Conclusions: The relative importance of major health determinants varies between income levels, thus extrapolating health policies from high- to low-income countries is problematic. Since the size, per se, of public health spending does not independently predict health outcomes, functioning health systems are necessary to make health investments efficient. Potential health gains from improved female education and economic growth should be considered in low- and middle- income countries.