Vieillissement prématuré, inégalités sociales de santé et environnement professionnel dans la cohorte GAZEL. – WORKAGE

Background & Objectives Most research on ageing does not focus on health in early old age despite the fact that this is a critical transition phase, and that disability and mortality risks in older age are reflections of conditions - including working factors - that occur throughout life. The focus of the WORKAGE project is to examine the ways in which work exposures over the lifecourse influence health outcomes in early old age: premature mortality, decrease in quality of life and physical and cognitive functional deficit, and to assess to what extent they may contribute to social inequalities. Most of the longitudinal studies on aging included subjects at a relatively old age, and do not have the opportunity of documenting in sufficient detail various occupational exposures over the active life. Our overarching hypothesis is that cumulative occupational exposures to different types of working factors accelerate the aging processes. We will analyze to what extent lifelong occupational exposures contribute to social health inequalities in older age, taking into account the influence of non-occupational factors associated to socioeconomic position. Methods Our proposal is based on the GAZEL Cohort Study, a longitudinal cohort established in 1989 among workers of Electricité de France – Gaz de France and followed continuously since then. The cohort is composed of 15,011 men and 5,614 women, now aged 54 to 69. There is a wide socioeconomic range of occupational positions. Data are collected from different sources: self-reports through annual questionnaires, data from the company, medical exams and mortality. We have detailed assessments of work-related exposures, health behaviours and other psychosocial conditions that are linked to data on quality of life and health outcomes. We propose to focus on a set of occupational exposures encompassing the main working conditions: psychosocial factors, ergonomic factors and chemicals. For each type of exposure, we will use job-exposure matrices to attribute cumulative lifelong exposure indices to the subjects. Various potential confounding or modifying factors, such as smoking, alcohol drinking, diet or physical activity, were also collected. The occupational factors will be analyzed, taking into account confounding or modifying factors, in relation to various aspects of aging: decrease of quality of life, physical and cognitive function deficit and premature mortality. There are two main components of our project. (1) analyses of the effect of occupational exposure for the entire cohort of 20,625. These subjects have data available since they were first employed and have annual follow-ups from 1989 to the present. (2) The collection and analysis of data to assess physical and cognitive function on a subsample of approximately 6,000 participants; in addition to all the data described for the entire cohort, these participants will have detailed standardized exam data on functioning. Conclusion One of the unique features of WORKAGE is that it is based on a large ongoing occupational cohort followed since almost 20 years; most of the participants are now retired and we have for them data on lifelong occupational exposures as well as on numerous potential confounding or modifying factors.