Younger, low-income Ontarians with diabetes have higher risk of death than their high-income counterparts

The gap between rich and poor is widening for Ontarians with diabetes and is leading to a 51 per cent higher risk of dying for those with lower socio-economic status, according new research by scientists at the Institute for Clinical Evaluative Sciences (ICES) and St. Michael’s Hospital.

While death rates have fallen substantially among those with diabetes due in large part to effective drug therapy; the study shows that low-income Ontarians with diabetes who are under 65 years of age have a higher risk of dying than their high-income counterparts.

“From our observations, as many as 5,000 deaths and nearly 2,700 heart attacks or strokes could have been avoided among younger and middle-aged adults with diabetes if the gap between wealthier and poorer individuals had been identical to that seen among older groups,” said Dr. Gillian Booth, lead author and ICES Scientist.

Although more effective, the cost of diabetes drug regimens have risen considerably over the past decade and the gap in mortality between richer and poorer patients with diabetes has widened in that time.

This population-based retrospective cohort study, using data from administrative health claims of more than 600,000 Ontarians with diabetes between April 1, 2002 to March 31, 2008, found that socio-economic status (SES) was a strong predictor of death and nonfatal heart attack or stroke among those under 65 years of age, but not among seniors. SES gradients were consistent for all age groups under 65. Similar findings were noted for 1-year post-heart attack mortality. SES was based on neighborhood median household income levels from the 2001 Canadian Census.

Looking at how people with diabetes are doing one year after a heart attack the study found income influences long-term survival; younger individuals in the lowest income category had 33 per cent higher rates of death one year later, compared to those of the same age in the highest income category.

“We found that younger and middle-aged people with diabetes (those under age 65) seem to be more susceptible to the effects of income,” said Booth, who is an endocrinologist at St. Michael’s Hospital. "Why does the impact of income vary so dramatically for different age groups? Although not measured directly, the study findings suggest that universal prescription drug coverage – available only after the age of 65 in Ontario – is a step that could potentially help bridge the gap in cardiovascular risk and death between rich and poor groups with diabetes.

More than 350 million people have diabetes worldwide and with the dramatic rise in obesity and the aging of the world’s population this figure is expected to double in the coming decades.

The study “Universal drug coverage and socioeconomic disparities in diabetes outcomes” is in the current issue of Diabetes Care.

Gillian Booth is a Scientist at the Keenan Research Centre, Li Ka Shing Knowledge Institute of St. Michael’s Hospital, an Adjunct Scientist at the Institute for Clinical Evaluative Sciences and an Associate Professor in the Department of Medicine at the University of Toronto.

Authors: Gillian L. Booth, Phoebe Bishara, Lorraine L. Lipscombe, Baiju R. Shah, Denice S. Feig MD MSc, Onil Bhattacharyya, Arlene S. Bierman.

This study was undertaken as part of the POWER (Project for an Ontario Women’s Health Evidence-Based Report) Study which provided a comprehensive overview of women’s health and healthcare in relation to income, education, ethnicity and geography.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

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