Depression and diabetes: The role of syndemics in the social inequality of disability

Abstract

Background: Most countries including Brazil have steep social gradients in the prevalence of disability. Many disorders contribute to that, and one individual often suffers from more than one disabling disease. The question is to what extent the syndemics framework that assume clustering and interaction between comorbid disorders influence the inequality in disability. Methods: We used the National Health Survey of Brazil (PNS 2013 N = 60.202 aged 18+ years), and studied prevalent self-reported disability, diabetes and depression. We estimated age- and sex-adjusted prevalence differences across levels of education and interactions as departure from additivity with linear probability models. Results: The Brazilian population shows social inequalities in the prevalence of both diabetes and depression, and the impact of the disorders on disability is differential, i.e. stronger among the low educated. There is both clustering and interaction between the two disorders, but the two mechanisms seem to play a negligible role in explaining the inequality in disability, whereas the most important mechanism is the differential impact the two disorders have on disability. A majority of patients suffering from both disorders has however a precarious position on the labor market with a combination of disability and only primary school or less education. Conclusion: The syndemics framework is helpful in understanding how comorbidities impact people's lives in a specific context of social inequality, and the interaction between clustering disorders are very visible on the population level. Clustering and interaction between diabetes and depression does not however contribute much to the social disparities in disability, but the group suffering from this comorbidity represent a significant need for vocational rehabilitation.