"Social capital," GNP per capita, relative income, and health: an ecological study of 23 countries.

The effects of social capital, income inequality, and absolute per capita income were investigated in an ecological analysis of 23 rich and poor countries. Trust was chosen as an indicator of social capital, and GNP (gross national product) per capita and Gini index measured absolute and relative income, respectively. These independent variables were analyzed in a linear regression model with the dependent variables adult mortality rate (25-64 years), life expectancy, and infant mortality rate (IMR). Separate analyses were performed for poor and rich countries as well as all countries combined. Social capital (trust) showed no significant association with the three health outcomes. A particularly strong relationship was found between Gini index and IMR for rich countries, and GNP per capita and life expectancy for all countries. In the group of poor countries, GNP per capita and Gini index in the same model were associated with IMR. The results contradict the suggested impact of social capital on health, and instead support the notion that economic factors such as absolute income and relative income distribution are of importance.