Understanding the impact of area-based composite measures on population differences in mortality: The Multiethnic Cohort Study - Life expectancy in the United States (U.S.) is approximately 78 years—notably lower than other high-income counties. Several factors contribute to this lower life expectancy, including elevated rates of chronic diseases, obesity, and inadequate access to healthcare services. An important but often underexamined dimension is the environment within which people live, work, and play. Research has consistently shown that our surrounding environment can profoundly influence health outcomes and affect premature mortality. Yet, few studies have investigated the interactive contributions of area-based factors on differences in mortality across population groups. We propose to investigate the impact of multiple domains of area-level factors on mortality for adults in the Multiethnic Cohort (MEC) Study using novel, composite measures at the geographic level of city, town, or Census designated place. Composite measures for distinct population groups will include indicators from the domains of housing; education; employment; healthcare; traffic; tobacco, alcohol and unhealthy food outlets; and environmental hazards as these factors have been shown to influence health behaviors and chronic diseases. Specifically, we aim to examine the impact of these composite area-based measures on all-cause mortality (Aim 1) and causespecific mortality (Aim 2), across population groups in the MEC and estimate years of life lost due to these composite measures. In addition, we will use causal inference methods to investigate whether individual-level health behaviors (smoking, diet, physical activity, alcohol use), comorbidities (diabetes, heart disease, cancer) and social support mediate the associations between composite area-based measures and mortality, and investigate these associations across subgroups defined by sex, life stage, and education. We will seek guidance from a multidisciplinary External Advisory Board and regional Community Advisory Board in the development of composite area-based measures, interpretation of study findings, and dissemination of the study measures and results. The findings from the proposed study will provide key evidence of the specific interacting area-based factors that should be targeted to improve the lifespan for population groups in the U.S. The impact of this research is high as it will have translational relevance in providing empirical evidence for community stakeholders, policy makers, and implementation scientists to direct interventions for reducing premature mortality.
