Caractérisation des inégalités sociales de santé parmi les personnes atteintes de diabète de type 2 – SEP & diabetes

Background: In 2007, 246 million adults worldwide (5.9% of the population) are estimated to have diabetes. Europe and North America have the highest prevalence rates. Despite major advances in treatment during the past decade, this 'epidemic' of diabetes remains a leading cause of death and disability. Socioeconomic position (SEP), measured at the individual (e.g., education, income) or at the community level, may have a profound impact on the morbidity and mortality associated with diabetes, suggesting that reducing social health inequalities among persons with diabetes may have a major public health impact. Such social health inequalities may result both from an independent role of SEP on health status of persons affected and from differences in the social impact of the disease according to SEP. Objectives: The primary objective of this project is to provide a greater insight into social health inequalities among persons with type 2 diabetes in two highly contrasted socio-cultural and health care contexts, i.e. France and USA. More specifically, our aim is to investigate in a complementary way both components of such inequalities, that is to characterize 1) the association between SEP and health status of persons with diabetes: what is its magnitude, in the absolute and compared to the non-diabetic population? Which pathways may explain this association? And 2) the impact of diabetes on a major dimension of individuals' social situation, i.e. work: what is the magnitude of this impact, in the absolute and compared to other chronic conditions? Do work consequences of diabetes differ according to SEP? What is the contribution of occupational and non-occupational factors in explaining such differences? Material: Large datasets providing detailed and complementary information on health, health determinants, SEP and occupational characteristics of persons with and without diabetes in France and in USA will be used: national health surveys in both countries (Enquête Décennale Santé [EDS] in France and National Health Interview Study [NHIS] in USA) provide cross-sectional information on large samples representative of the general population; large prospective cohorts, i.e. the Atherosclerosis Risk in Communities Study (ARIC) in USA and the GAZEL cohort in France provide longitudinal information on individuals selected from the general population (ARIC) or from a large national company (GAZEL) and followed for over 15 years; Project Sugar 2 provides longitudinal information on a sample of selected diabetic patients in USA included in an intervention trial aimed at improving health behaviours. Projected analyses: In a first part, analyses will focus on the association between SEP and health status of persons with diabetes. Social health disparities among this population will be measured and their magnitude compared i) over time and ii) with that of disparities encountered among the non-diabetic population. Mechanisms of the association between SEP and health among persons with diabetes will be investigated by i) measuring the independent associations between each of the various dimensions of individuals' SEP (individual adult/childhood SEP; neighbourhood SEP) and their health status; and ii) estimating the respective role of health behaviours, access to care, process of care and that of various 'distal' mediating/moderating factors (e.g., social support or depression) in explaining these associations. In a second part, analyses will focus on the work consequences of diabetes. These analyses will include participants of the GAZEL cohort of working age and in activity. Various indicators of occupational situation will be used: disability; early retirement; sickness absence; occupational mobility. Individuals' occupational situation will be compared over follow-up time, adjusting for major socioeconomic and occupational determinants of this situation, between those with diabetes and i) those without any chronic condition, ii) those affected by another chronic condition. The magnitude of social inequalities in the work consequences of diabetes will be estimated by measuring the association between SEP and the evolution of the occupational situation among individuals with diabetes. Adjustment on occupational characteristics and indicators of physical and mental health status will allow estimating the part of this association explained by such factors. Expected repercussions: In a field where international and intercultural work is strongly needed to better document the social stratification of health problems, this project will provide essential information for an improved knowledge of the situation regarding social health inequalities among persons with diabetes and for the understanding of the mechanisms underlying such inequalities. Such information is required to drive policy making in order to alleviate the individual and societal burden of diabetes in particular and chronic disease in general.