Arkansas Neighborhoods With Long Hospital Drive Times Have Higher Rates of AMI Mortality

Home is where the heart is, the saying goes, but a new study suggests that mortality following an acute MI is also linked with where that home is located. In a new analysis of neighborhoods throughout Arkansas, those living furthest from a PCI-capable hospital had a significantly increased risk of dying compared with those who lived closer.

At the neighborhood level, there was a 26% increased risk of acute MI mortality as driving time to the nearest PCI-capable hospital increased, even after plausible confounders, report investigators.

When investigators compared two maps—the map detailing the neighborhoods with the highest relative risk of mortality after acute MI and those neighborhoods with the longest driving times to the nearest PCI-capable hospital—the two maps were nearly superimposable. “Driving time seems to be a big predictor for mortality in some of these small, rural, underserved neighborhoods,” said lead investigator Appathurai Balamurugan, MD, University of Arkansas for Medical Sciences College of Medicine in Little Rock.

The results of the study are published February 16, 2016 in the Journal of the American Heart Association.

Not Entirely Surprising News

Speaking with TCTMD, Balamurugan, who also serves as the medical director of the chronic disease division at the Arkansas Department of Health, said a 2013 report showed that Arkansas had the highest age-adjusted death rates from MI in the US, nearly 30% higher than the second-ranked state. Although the finding "was alarming”, it was not entirely surprising news. When this information emerged, officials wanted to understand why the mortality rates following acute MI were so high.

In the analysis, investigators documented 14,027 acute MI deaths that occurred in 2008 to 2012. They examined the relationship between driving time from the population center of various neighborhoods to the nearest PCI-capable hospital. The analysis drilled down to the “micro” level, said Balamurugan, noting that similar analyses conducted elsewhere typically study county-level demographics and hospital driving times.

They identified 2,147 “census block groups,” which served as proxies for neighborhoods in Arkansas, and assigned acute MI deaths to each block group. The relative risk of death following acute MI in each neighborhood was then estimated based on a standardized mortality ratio. In doing so, the researchers identified a more than 3-fold difference in the relative risk of acute MI mortality across the state, even among adjacent neighborhoods. The neighborhoods with the highest relative risk were located in Eastern Arkansas in the Mississippi Delta regions.    

Next, the researchers calculated the median driving distance taking the shortest path and driving time from the population center of the neighborhood to the nearest PCI-capable hospital. The median distance and drive times—at 12.8 miles and 28.3 minutes—are both significantly higher than in other states. In the US, the median driving distance to a PCI-capable hospital is 7.9 miles and driving time is 11.3 minutes.

After adjusting for multiple variables, including education levels, poverty, population density, rurality, race, and mobility, the researchers still observed a significantly elevated risk of death following acute MI among individuals with significantly longer driving times to the nearest PCI-hospital (comparing those in the 90^th percentile for driving time vs those in the 10^th percentile).

“It’s a telling sign that something has to be done,” said Balamurugan.

Challenges Unique to Arkansas

In Arkansas, the median distance to a PCI-capable hospital is 30% than the national average, but the driving time is approximately 2.5-fold longer. The reason is that neighborhoods in the western part of Arkansas contain the Ozark and Ouachita mountains while the eastern state is bisected by the Arkansas, Mississippi, White, and St. Francis rivers. As the researchers point out, these natural barriers contribute to longer driving times.

To TCTMD, Balamurugan noted that 21% of the state’s population—those 35 years of age and older—live more than 60 minutes from the hospital. In other words, 362,000 individuals would be unable to get to a PCI-capable hospital within the “golden hour” for timely coronary revascularization. “Of course, when you talk about the time, it doesn’t include time for the ambulance to arrive and the scene time,” said Balamurugan. All of this adds up to an extended amount of time before acute MI patients undergo PCI.

While the state has challenges, it’s not all “doom and gloom,” said Balamurugan. Public health officials and legislators have been working to ensure individuals are aware of the signs and symptoms of MI so they call 911. At present, too many people are failing to call an ambulance when these signs and symptoms come on, with approximately one third of individuals still arriving at hospital on their own, either driving themselves or having a family member take them. They are also working to ensure all counties in Arkansas have dedicated emergency medical services (EMS). Right now, not every county has EMS coverage, with some relying on neighboring counties for care.

At the systems-wide level, they are also working on improving the readiness of healthcare systems in response to acute MI patients. At present, the Arkansas Department of Health is working with the American Heart Association on quality-improvement programs, such as Mission: Lifeline, to implement systems of care for STEMI patients. In addition, the state received a two-year grant to establish protocols for STEMI care based on the success of the Reperfusion of Acute Myocardial Infarction in Carolina Emergency Departments (RACE) project conducted by Duke Clinical Research Institute. 

Source:
Balamurugan P, Delongchamp R, Im L, et al. Neighborhood and acute myocardial infarction as related to driving time to percutaneous coronary intervention-capable hospital. J Am Heart Assoc 2016;Epub ahead of print.   

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