The shape of the relationship between income and self-assessed health: an international study.

BACKGROUND: The relationship between income and health is usually thought to be curvilinear, but previous studies have yielded inconsistent results. We therefore examined the shape of the relationship between household equivalent income and self-assessed health in seven European countries. METHODS: Data were obtained from nationally representative health, level of living, or similar surveys in Belgium, Denmark, England, Finland, France, The Netherlands, and Norway and applied to men and women aged 25 years and older in the 1990s. Smooth nonparametric curves were fitted to the data, as well as a spline regression function with three linear pieces connected by two knots. RESULTS: A higher household equivalent income is associated with better self-assessed health among men and women in all countries, particularly in the middle-income range. In the higher income ranges, the relationship is generally curvilinear and characterized by less improvement in self-assessed health per unit of rising income. In the lowest income ranges, the relationship is found to be curvilinear in four countries (Belgium, Finland, The Netherlands, and Norway), where the usual deterioration of health associated with lower incomes levels off or even reverses into an improvement. CONCLUSIONS: Further research is necessary to investigate the background of differences between countries in the shape of the relationship between income and self-assessed health, and should focus on both methodological and substantive explanations. Assuming causality, the results of our study lend some support to the notion of decreasing marginal health returns of a unit increase in income at the higher income ranges.

Trends in socioeconomic inequalities in self-assessed health in 10 European countries.

BACKGROUND: Changes over time in inequalities in self-reported health are studied for increasingly more countries, but a comprehensive overview encompassing several countries is still lacking. The general aim of this article is to determine whether inequalities in self-assessed health in 10 European countries showed a general tendency either to increase or to decrease between the 1980s and the 1990s and whether trends varied among countries. METHODS: Data were obtained from nationally representative interview surveys held in Finland, Sweden, Norway, Denmark, England, The Netherlands, West Germany, Austria, Italy, and Spain. The proportion of respondents with self-assessed health less than 'good' was measured in relation to educational level and income level. Inequalities were measured by means of age-standardized prevalence rates and odds ratios (ORs). RESULTS: Socioeconomic inequalities in self-assessed health showed a high degree of stability in European countries. For all countries together, the ORs comparing low with high educational levels remained stable for men (2.61 in the 1980s and 2.54 in the 1990s) but increased slightly for women (from 2.48 to 2.70). The ORs comparing extreme income quintiles increased from 3.13 to 3.37 for men and from 2.43 to 2.86 for women. Increases could be demonstrated most clearly for Italian and Spanish men and women, and for Dutch women, whereas inequalities in health in the Nordic countries showed no tendency to increase. CONCLUSIONS: The results underscore the persistent nature of socioeconomic inequalities in health in modern societies. The relatively favourable trends in the Nordic countries suggest that these countries' welfare states were able to buffer many of the adverse effects of economic crises on the health of disadvantaged groups.