People living in U.S. counties with the highest rates of poverty are more likely to die from heart failure than those from more affluent areas, a new study suggests.

Researchers examining data from more than 3,000 U.S. counties found that for each percentage-point increase in poverty, heart failure mortality increased by 5.2 deaths per 100,000 county residents, according to the report published online in the Journal of the American Heart Association.

After adjusting for other factors that could contribute to heart failure outcomes, about two-thirds of the effect of poverty on heart failure mortality was explained by rates of diabetes and obesity, researchers noted.

“The potential mechanisms we investigated showed that the degree of obesity and diabetes at the county level correlated with both the degree of poverty and the degree of heart failure,” said study coauthor Wen-Chih Wu, chief of the cardiology section at the Providence VAMC in Rhode Island and medical director of the Lifespan Cardiovascular Rehabilitation Program at Brown University.

The best way to improve heart health for the poor would be to “target high-poverty areas and develop policies to target risk factors for diabetes and obesity through healthy foods availability, space for physical activity and increase access to primary care as well as heart specialists,” Wu said in an email.

To study the impact of poverty on death from heart failure, the researchers analyzed data from the Centers for Disease Control and Prevention and the U.S. Census Bureau for 3,135 U.S. counties.

They focused on five socioeconomic variables: proportion of residents living in poverty, median county household income, unemployment rate, proportion of the population aged 25 and older without a high school diploma, and the proportion without health insurance.

In their analysis, the researchers adjusted for diabetes and obesity, as well as for physical activity and patterns of medication adherence. Data on mortality from 2012 to 2014 came from death certificates published by the National Center for Health Statistics.

Among the counties analyzed in the study, the median poverty rate was 15.8%. Median heart failure mortality was 189.5 deaths per 100,000 residents. The difference in the number of heart failure deaths between the county with the lowest poverty rate, at 3.2%, and the highest, at 52.2%, was 254.8 deaths per 100,000 residents.

Overall, the researchers calculated, poverty explained about 30% of the variation between counties in heart failure mortality rates.

They also found the impact of poverty on heart failure mortality varied geographically: the poverty effect was much stronger in the South than in the Northeast.