Prospective cohort study on the social determinants of health: Tehran University of Medical Sciences employees' cohort (TEC) study protocol

Background: In this study, the association between the social determinants of health (SDH) as well as other health risk factors and outcomes will be evaluated at different socioeconomic layers. Methods/design: This is a prospective cohort study that was launched in January 2018 on Tehran University of Medical Sciences' employees. The initial enrolment phase will continue up to March 2021, or until a sample size of 5500 is reached. In addition to annual phone-calls, the participants will be followed thrice at 5-year intervals. Data are collected through blood and urine samples, complete physical examination, anthropometric evaluation, and the completion of questionnaires related to SDH, such as socioeconomic status and social capital, history of diseases, lifestyle (including, nutrition, physical activity, cigarette and hookah smoking), occupational exposures (including psychosocial factors at work and work-family conflicts), and different aspects of physical, mental and occupational health as health outcomes. The association between independent variables and health (objective or subjective) are examined using multiple models and by controlling the confounding effects. Moreover, the trend in lifestyle changes and its impact on health are evaluated. Discussion: Our study will explore the key social determinants as well as other factors including socioeconomic status and social capital, history of diseases, lifestyle and occupational exposures that affect health. This will provide social and occupational health decision-makers and stakeholders with new and valuable evidence in an era in which we are witnessing huge changes in lifestyle.