Association Between Neighborhood-Level Income and the Incidence of Cardiovascular Events Varies by Immigration Status: A Population-Based Cohort Study.

Abstract

Background: Neighborhood-level income is inversely associated with cardiovascular events; however, it is uncertain whether this association varies with immigration status.

Methods and results: We conducted a population-based cohort study of 5.2 million (53% women, 19% immigrants) urban-dwelling people aged ≥40 years without a prior history of cardiovascular disease in Ontario, Canada. Neighborhood-level income was measured in quintiles from quintile 1 (lowest) to quintile 5 (highest), and immigrants were defined as those born outside of Canada who moved to Canada after 1985. We estimated the association between neighborhood-level income and the rate of incident cardiovascular events (hospitalization for stroke or myocardial infarction, or cardiovascular death) using multivariable cause-specific hazards models and added an interaction term to see if the association varies by immigration status. The absolute difference in the rate of cardiovascular events across income quintiles was less pronounced in immigrants than in long-term residents: age- and sex-adjusted rate per 1000 person-years in quintile 1 versus quintile 5: 5.69 versus 4.10 in immigrants and 8.37 versus 5.87 in long-term residents. In adjusted models, the interaction between immigration status and neighborhoodl evel was significant (P_interaction <0.001). The hazard of cardiovascular events declined with increasing income among long-term residents (hazard ratio [HR]_Q1vsQ5, 1.46 to HR_Q4vsQ5, 1.10) and immigrants, albeit with a smaller gradient (HR_Q1vsQ5, 1.43 to HR_Q4vsQ5, 1.20).

Conclusions: The association between neighborhood-level income and cardiovascular disease incidence varies by immigration status. Understanding the social and structural factors associated with residing in low-income neighborhoods can help with the development of prevention programs that improve health for all.