Understanding young adults’ socioeconomic circumstances and their contribution to social inequalities in smoking during the transition towards adulthood

Social epidemiology has demonstrated the importance of early life periods such as childhood and adolescence for understanding the development of health inequalities over the life course. New issues, however, challenge us to question the role of young adulthood (i.e., ages 18–25) as a new, sensitive period during this time. Smoking clearly illustrates this issue. Today, approximately 30% of Canadians who smoke their first cigarette, and 40% of Canadians who become daily smokers, do so after the end of adolescence. Despite the successes of tobacco control with other age groups, it has not seen any decrease in initiation and cessation rates in young adult Canadians since the beginning of the 21st century. Smoking behaviour during young adulthood occurs in rapid transitions in and out of education, employment, family, and housing circumstances, which are unequally experienced across social groups. The interplay of these experiences, therefore, requires the development of theoretical and analytic frameworks to better understand the unequal progression of smoking during the transition to adulthood. This thesis presents four articles that provide theoretical insight into, and robust evidence of, the socio-economic circumstances through which young adults progress and the mechanisms through which these circumstances influence smoking. Article 1 starts with a methodological systematic review of social inequalities in smoking among young adults, focusing on the indicators used to operationalize socio-economic circumstances. Based on 89 articles, the review demonstrates that tobacco research has relied disproportionately on a few traditional indicators to understand social inequalities in smoking during this period, leaving us with inconsistent findings and a significant knowledge gap. In response, I develop a theoretical proposal based on an integration of Bourdieu’s practice theory with life-course studies to guide the study of young adults’ socio-economic circumstances. This is accomplished by disentangling the interplay of economic, social, and cultural resources to which young adults have access from the transition stages and the different ages through which they progress during this period. The heart of the thesis tests this proposal based on three empirical studies using two data sets: (1) the Interdisciplinary Study of Inequalities in Smoking (ISIS), which recruited 2,093 young adults aged 18 to 25 in Montreal, Canada, in 2011–2012; and (2) the National Population Health Survey (NPHS), which followed 1,243 young adult Canadians between the ages of 18 and 25 every two years from 1994 to 1995 and 2010 to 2011. Using ISIS data, Article 2 demonstrates the diversity of resources and transition stages that contribute to the unequal distribution of smoking. This article also illustrates how the associations between resources, transition stages, and smoking may be exacerbated across social groups defined by educational attainment. Article 3 complements these findings by demonstrating that many of these same resources and transition stages also have a different association with smoking depending on the exact age at which they are experienced. Using NPHS data, Article 4 further supports these findings by demonstrating how the associations between resources, transition stages, and smoking unequally develop across education groups during the transition to adulthood, rapidly changing between the ages of 18 and 25. This thesis makes a unique contribution to public health by helping us better understand the configuration of young adults’ socio-economic circumstances and its contribution to social inequalities in smoking during the transition to adulthood. It offers strong tools to support researchers’ capacity to integrate the dynamic context of young adulthood into the study of health inequalities. Finally, this thesis demonstrates that efforts to combat health inequalities must be led by intersectoral approaches, which support individuals across education, employment, family, and housing circumstances so that each person may equitably develop their health over the course of their lives.

Keyphrases: Canada, Young adults, Smoking, Social inequalities