A longitudinal analysis of the relationship between changes in socio-economic status and changes in health.

In this paper we contribute to discussion on the relationship between different aspects of socio-economic status (SES) and health. Separating different aspects of SES facilitates the specification of a structural relationship between SES indicators and morbidity. Longitudinal data and the utilization of growth curve modelling enable an empirical analysis of the direct relationship between changes over time in SES indicators and changes in morbidity. Our empirical analysis is based on panel data (N = 2976) derived from the annual Swedish Survey of Living Conditions. The panel, which consists of respondents that at the first panel wave were between 31 and 47 years old, is followed for 16 years, starting in 1979. Data are gathered at three points of time. A growth curve model is set up using structural equation modelling. The structural relationship and changes over time are simultaneously estimated. It is shown that in relation to health occupational position is crucial, canalising the effects of class of origin and education. More prestigious jobs are related to initially good health and to a less rapid deterioration in health. At the same time initial health affects occupational mobility, confirming a health selection into less prestigious jobs. It is also shown that change of occupation and income are related to change in health. The analysis confirms a strong relationship between SES and morbidity and shows that initial SES affects later changes in morbidity, i.e., a causal relationship exists between SES and morbidity. But, the analysis also demonstrates the existence of selection effects, meaning that initial morbidity causes less favourable changes in SES. It is finally revealed that changes in occupational prestige and income changes co-vary with changes in morbidity. Hence, the analysis provides basic information necessary to make any assumption about causality and selection in relation to SES and health.