Epidemiological studies of the social context of illness and sickness

Sammanfattning: Epidemiological studies of the social context of illness and sickness by Nelson Blank, Karolinska Institutet, Department of Public Health Sciences, Division of Social Medicine, SE- 172 83 Sundbyberg, Sweden The overall objective of this thesis is to contribute to the theoretical and methodological development of research aiming to explain diversity in experiences of illness and sickness. Special attention is paid to the relationships between objective life conditions, personal circumstances and perceptions of well-being. The thesis is based on five separate empirical studies employing data from the Swedish Surveys of Living Conditions (ULF) over the years 1979-1989, conducted by the Survey Research Institute, Statistics Sweden. The first paper has a cross-sectional design and addresses questions about tbe role played by socioeconomic conditions in distinguishing between persons who report different degrees of suffering in terms of intensity and frequency of long-term illness and the extent that socioeconomic classes report different expenences of illness because of differential consequences and/or exposures to a set of living conditions. The results lend support to the hypothesis that manual classes are subjected to what might be called "double suffering", in the sense that they present more long-term illnesses and also experience these illnesses with greater intensity and frequency. Paper II has a longitudinal design aimed at analyzing the role played by socioeconomic factors and self-rated general health in the prediction of the reporting of severe long-term illness, and the extent to which these factors explain social-class differences in the reporting of such illness. Socioeconomic and individual factors predict severe long-term illness regardless of kind of reported disorder. The main predictive factor involved is health self-rated as fair/poor, but exposure to high physical job demands is the main factor explaining the role played by class. The results of the study strengthen the hypothesis that manual workers are not only more exposed to causes of illness that have important individual and social consequences, but also to the personal factors that determine different experiences of illness. The interaction found between job demands and self- rated health suggests that socioeconomic and individual factors play different but complementary roles in the causal process leading to the expenence of severe long-term illness. Paper III is a cross-sectional study which analyzes similarities and differences between repeated spells of short-term sick leave and long-term sick leave in relation to variables representing certain social circumstances and aspects of work situation. Particular attention is paid to gender differences. Tbe results suggest the existence of a common mechanism via which a variety of factors are related to both repeated short-term and long-term sick leave. Gender differences with regard to the effect of work conditions on sick leave should be regarded in the light of factors related to occupational structure. We found a less than additive effect of physical job demands and repeated short spells of sick leave on subjective health, suggesting that repeated short spells may counteract the deleterious effects on health of high physical job demands. Paper IV studies the way relative poverty, as measured by low household disposable income or the presence of personal financial crisis, affects health measured in terms of self-reported sleep problems in a representative Swedish sample of employed persons aged 20-65. The results reveal a conditional relationship between poverty and sleep problems. Modifying effects of factors such as unemployment expenence, divorce and long- term illness are tested, as too are the buffer effects of social networks and smoking habits. A conditional relationship is found between poverty and sleep problems. The effect of poverty among men is modified by previous expenence of unemployment; while, among women, the effect is buffered by strong social networks but aggravated by smoking. The possible meanings of the observed effect modifications are discussed. Paper V is a longitudinal study which analyzes the interaction between socioeconomic and personal circumstances in relation to inequalities in health. It is based on a theoretical framework which presupposes that inequalities in health are likely to be explained by a complicated process simultaneously involving differential exposures and differential responses to risk factors between classes. The necessity of highlighting in further research the complex interactions and pathways between factors associated with health outcomes is emphasized. Only then can our understanding of the causal processes involved be improved, and appropnate preventive measures determined. Key words: Reported morbidity, illness, health inequalities, self-rated health, health status, social class, sickness absence, sick leave, interaction