UNDERSTANDING HEALTH INEQUITIES IN NONCOMMUNICABLE DISEASES: AN EPIDEMIOLOGICAL PERSPECTIVE USING THE SYNDEMIC FRAMEWORK

This thesis employs a syndemic framework to examine how social and structural inequities influence the development, co-occurrence, and progression of non-communicable diseases (NCDs). Combining epidemiological methods and anthropological and social theory, it aims to move beyond individual-level risk factors and to describe the processes through which socioeconomic inequalities shape disease clustering. Specifically, the thesis applies the syndemic framework to two longitudinal cohorts, the Piedmont Longitudinal Study (Italy) and the UK Biobank (United Kingdom), and across different combinations of diseases. The first study investigates the co-occurrence of chronic kidney disease (CKD) and cardiovascular disease (CVD), showing an association between CVD risk and CKD. It also provides evidence that the risk of developing CVD is disproportionately concentrated among individuals with lower socioeconomic position (SEP). The second study expands on this analysis by incorporating the syndemic framework to examine the relationship between CKD or end-stage renal disease (ESRD), CVD, and SEP, and their association with all-cause mortality and emergency room admissions for life-threatening causes. The results highlight differences in risk across socioeconomic groups, suggesting that the intersection between disease clustering and social determinants of health contributes to the unequal distribution of severe outcomes. The third study extends the syndemic framework to a different set of diseases, steatotic liver disease (SLD) and cancer, in combination with SEP (defined as a composite of income, education and employment status), within the UK Biobank cohort. The findings showed that SLD is associated with an increased risk of any cancer, particularly obesity-related and digestive cancers. Moreover, these associations are amplified in individuals with low SEP. The fourth study draws inspiration from a well-documented comorbidity and syndemic cluster: type 2 diabetes mellitus (T2DM) and depression. Building on the syndemic approach, it examines the clustering of T2DM, depression, education, and place of birth in the Piedmont cohort. T2DM and depression co-occur with low educational attainment, with patterns differing by sex and migration background. Collectively, these studies illustrate how the syndemic framework can integrate clinical and social perspectives to examine the clustering of NCDs. The evidence shows that chronic disease co-occurrence is shaped not only by biological mechanisms but also by social and structural conditions. The findings highlight the relevance of prevention and policy strategies that address social determinants alongside clinical management to support more equitable health outcomes across populations