Growing income-related disparities in cardiovascular hospitalizations among people with diabetes, 1995 to 2019: population-based study

Objective: Cardiovascular risk reduction is an important focus in the management of people with diabetes. Although event rates have been declining over the long-term, they have been observed to plateau or reverse in recent years. Furthermore, the impact of income-related disparities in cardiovascular events is unknown. The objective of this study was to evaluate age-, sex- and income-related trends in cardiovascular hospitalization rates among people with diagnosed diabetes.

Research Design and Methods: We calculated rates of hospitalization for acute myocardial infarction, stroke, heart failure and lower extremity amputation in annual cohorts of the entire population of Ontario, Canada with diagnosed diabetes, from 1995 to 2019. Event rates were stratified by age, sex and income level.

Results: We studied nearly 1.7 million people with diabetes. The rate of acute myocardial infarction declined throughout the 25-year study period (p<0.0001), such that the rate in 2019 was less than half the rate in 1995. Rates of stroke (p<0.0001), heart failure (p<0.0001) and amputation (p<0.0001) also changed over time, but hospitalization rates stabilized through the 2010s. This apparent stabilization concealed a growing income-related disparity: wealthier patients showed continued declines in rates of these outcomes during the decade, whereas rates for lower-income patients increased (p for interaction <0.0001 for all 4 outcomes). 

Conclusions: During a quarter-century of follow-up, cardiovascular hospitalization rates among people with diabetes fell. However, the apparent stabilization in rates of stroke, heart failure and amputation in recent years masks the fact that rates have risen for lower-income individuals.