"Trends in socioeconomic inequalities in premature and avoidable mortality in Canada, 1991–2016": Newly published journal article in the CMAJ co-authored by Sociology MA student Abtin Parnia

October 1, 2020 by Jeremy Nichols

MA student Abtin Parnia recently co-authored a paper entitled, “Trends in socioeconomic inequalities in premature and avoidable mortality in Canada, 1991–2016” in the CMAJ. The authors find that mortality inequalities between the rich and poor is widening in Canada.  One of the reasons for this increasing inequality is likely the retrenchment of the welfare state, precarious employment situation, and other neoliberal policies of the last several decades.

Abtin Parnia is currently enrolled in the Sociology Masters program at the University of Toronto.  They have a Master’s in Public Health with a specialization in Epidemiology from Dalla Lana School of Public Health at University of Toronto. Abtin previously worked at Cancer Care Ontario, MaRS Discovery District and since 2018 as a Research Data Analyst in Dr. Arjumand Siddiqi’s Social Epidemiology Research Group at University of Toronto.

Abtin’s current research examines how health inequalities change over time and what are the mechanisms that produce and maintain social inequalities, particularly looking at health inequities by race, migration, and socioeconomic status. Abtin's current supervisor is Dr. Monica Alexander.

We have posted the abstract of the paper below. The full paper is available here.


BACKGROUND: Recent epidemiologic findings suggest that socioeconomic inequalities in health may be widening over time. We examined trends in socioeconomic inequalities in premature and avoidable mortality in Canada.

METHODS: We conducted a population-based repeated cohort study using the 1991, 1996, 2001, 2006 and 2011 Canadian Census Health and Environment Cohorts. We linked individual-level Census records for adults aged 25–74 years to register-based mortality data. We defined premature mortality as death before age 75 years. For each census cohort, we estimated age-standardized rates, risk differences and risk ratios for premature and avoidable mortality by level of household income and education.

RESULTS: We identified 16 284 045 Census records. Between 1991 and 2016, premature mortality rates declined in all socioeconomic groups except for women without a high school diploma. Absolute income-related inequalities narrowed among men (from 2478 to 1915 deaths per 100 000) and widened among women (from 1008 to 1085 deaths per 100 000). Absolute education-related inequalities widened among men and women. Relative socioeconomic inequalities in premature mortality widened progressively over the study period. For example, the relative risk of premature mortality associated with the lowest income quintile increased from 2.10 (95% confidence interval [CI] 2.02–2.17) to 2.79 (95% CI 2.66–2.91) among men and from 1.72 (95% CI 1.63– 1.81) to 2.50 (95% CI 2.36–2.64) among women. Similar overall trends were observed for avoidable mortality.

INTERPRETATION: Socioeconomically disadvantaged groups have not benefited equally from recent declines in premature and avoidable mortality in Canada. Efforts to reduce socioeconomic inequalities and associated patterns of disadvantage are necessary to prevent this pattern of widening health inequalities from persisting or worsening over time.

A decade after the release of the World Health Organization’s final report on the social determinants of health, governments around the world appear to have made relatively little progress toward the goal of reducing health inequalities. In fact, recent epidemiologic findings suggest that socioeconomic inequalities in mortality and related indicators of population health are widening over time. Such trends are well established in the United States and Europe, yet analogous trends in Canada remain poorly characterized. Efforts to monitor the evolution of socioeconomic inequalities in mortality in Canada have been hampered by the fact that official death records lack information on the socioeconomic status of deceased people. In the absence of this information, some investigators relied on area-based measures of socioeconomic deprivation to monitor change in mortality inequalities in Canada. More recently, however, researchers have overcome this methodologic barrier by linking vital statistics records to individual Census data that contain relevant indicators of socioeconomic status.

Notably, existing analyses of individual-level trends in the mortality gradient in Canada have focused on the adult population as a whole and, in so doing, have obscured from view an important source of survivorship bias. Prior research has shown that those who survive into older adulthood represent a highly selected group and that positive selection for the most robust people is particularly strong at the lower end of the socioeconomic spectrum. This pattern of selective survival leads to the gradual convergence of average health levels over time, which, in turn, attenuates the association between socioeconomic status and mortality in older age groups. A common approach to dealing with this form of downward selection bias involves excluding the “oldest old” and focusing attention on socioeconomic inequalities in premature and avoidable mortality among adults younger than age 75 years.

In the present study, we aimed to examine trends in socioeconomic inequalities in premature and avoidable mortality between 1991 and 2016 in Canada using linked Census and vital registration data.