ARTICLE IN BRIEF
Using death certificates from 3,110 counties in the United States, researchers reported the overall rate of death from cardiovascular diseases fell in the past 35 years, but they also identified persistent and major disparities in certain counties — some of which were outside of the previously identified “stroke belt.”
The regional differences in cardiovascular mortality in the United States are a well-documented phenomenon, but county-level disparities of specific cardiovascular diseases have only been partially understood. Now, in a paper published in the May 16 issue of Journal of the American Medical Association (JAMA), Gregory A. Roth, MD, MPH, an assistant professor in the division of cardiology at the University of Washington, and colleagues, provide a more granular look at those statistics.
Reviewing mortality rates from all major cardiovascular conditions by US county between 1980 and 2014, they found that, although cardiovascular diseases continue to be the leading cause of death in the US, the overall mortality rate from these diseases has been cut in half (50.2 percent) — a major achievement.
Using death certificates from 3,110 US counties, Dr. Roth and colleagues reported the overall rate of death from cardiovascular diseases fell from 507.4 deaths per 100,000 people to 252.7 deaths per 100,000 people. But the researchers also discovered persistent and major disparities in certain counties — some of which were outside of the previously identified “stroke belt” (typically identified as 11 states, including Alabama, Arkansas, Georgia, Indiana, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia).
Conditions, such as atrial fibrillation, endocarditis, and peripheral arterial disease, had actually increased in overall mortality during the time frame, they reported. Other conditions where disparities continued to be significant as recently as 2014 included hypertensive heart disease mortality (counties at the 90th and 10th percentiles reporting 17.9 and 4.3 deaths per 100,000 people, respectively), ischemic heart disease (235.7 and 119.1 deaths per 100,000 people in the 90th and 10th percentiles), and cerebrovascular disease (68.1 and 40.3 deaths per 100,000 people in the 90th and 10th percentiles).
“The largest concentration of counties with high cardiovascular disease mortality extended from southeastern Oklahoma along the Mississippi River Valley to eastern Kentucky, and several cardiovascular disease conditions were clustered substantially outside the South, including atrial fibrillation (Northwest), aortic aneurysm (Midwest), and endocarditis (Mountain West and Alaska),” the authors wrote. Mortality rates were the lowest in the areas around San Francisco in California, central Colorado, northern Nebraska, central Minnesota, northeastern Virginia, and southern Florida.
“A broader exploration of the quality of both facility- and community-based health interventions in the lowest- and highest-risk counties would be an important first step in reducing cardiovascular disease differences,” Dr. Roth and colleagues concluded. “Counties with successful implementation of broad-based interventions to reduce cardiovascular disease have been well described. In particular, better county-level data are needed on dietary exposures, prehospital care, and access to high-quality chronic disease care.”
Michael Dobbs, MD, professor of neurology at the University of Kentucky and director of the Norton Healthcare/UK HealthCare Stroke Care Network in Lexington, told Neurology Today that he was “not surprised by most of the locations where the disease burden was highest, because we already knew that these geographic areas tended to show high rates of uncontrolled risk factors for vascular disease.” However, he noted that the report also shows that mortality from these preventable vascular diseases can improve over time in many geographic areas, which should be encouraging to those regions where disparities still exist.
Virginia J. Howard, PhD, professor in the department of epidemiology at the University of Alabama School of Public Health and a co-principal investigator on the Reasons for Geographic and Racial Differences in Stroke (REGARDS) and Carotid Revascularization Endarterectomy vs. Stenting Trial (CREST) studies, applauded the study design of the JAMA article. A major strength of this paper compared with other studies is the way the research team defined causes of death, she said, by cleaning up “garbage codes” from the death certificates (using algorithms developed for the Global Burden of Disease study) to ensure that all deaths were assigned exactly one cause.
One difficulty with these types of studies is that they must rely on death certificates — there is no single national stroke and cardiovascular disease registry in the US, she explained. “We sense that the decline in stroke mortality is somewhat related to incidence but we don't have national data to confirm that — and we don't know, for instance, if it's declining for all race and ethnic groups.” She cited a January 2014 statement from the American Heart Association/American Stroke Association published in Stroke, which declared “a real decline in stroke mortality” that can be linked at least in part with the declining incidence of stroke.
The first important takeaway from the report is that mortality has been significantly reduced, so that's a major improvement. said Camilo R. Gomez, MD, MBA, FAAN, professor of neurology and neurosurgery and vice-chair of the department of neurology at Loyola University Medical Center in Maywood, IL. “The second message is that there are differences in the degree of mortality in various regions of the country — and we've known that for some time — but the question remains why?” One of the most interesting queries raised by this study, he added, is why, with the same risk factors, disparities exist only for certain subsets of cardiovascular diseases — “you can't superimpose one map on the other. I find that fascinating.”
Agreeing, Dr. Howard said these areas with large disparities are worth deeper study. “We can learn a lot from figuring out what is so drastically different in those counties. We know higher socioeconomic status is a big part of it, but it's [also] important to look at related factors like healthy environments and safe walking paths. The social determinants of health are a big factor but those are more difficult to change.” Dr. Howard suggested that small, community-level changes could be an important start.
“The findings of marked geographic disparities in CVD [cardiovascular disease] mortality described by Roth et al serve as a critical reminder to challenge clinicians, investigators, and public health leaders to imagine a future in which an individual's risk of cardiovascular death is no longer determined by ‘the place’ he or she was born or resides and no longer prevents pursuing a healthy and fulfilling life,” wrote George A. Mensah, MD, a senior advisor in the Immediate Office of the Director at the National Heart, Lung, and Blood Institute (NHLBI), and colleagues, in an accompanying editorial published in the May 16 issue of JAMA.
NEXT STEPS, FUTURE RESEARCH
How do neurologists, particularly in counties that need the most improvement, incorporate these data into practice? “Perhaps groups like the VA that have everyone in one system and can track migration throughout the country might be able to study when people develop some of the risk factors, such as hypertension and diabetes, so we can intervene earlier,” Dr. Howard suggested. Different groups need to work together to gather research and data, she said, noting that the National Institute of Neurological Disorders and Stroke has funded the REGARDS study since 2001.
Dr. Gomez told Neurology Today that the JAMA paper reiterates the need to focus on local-level research and interventions. “I think this relates to a major philosophical conundrum that we are facing in all areas of medicine between epidemiologic data and national campaigns, which are geared towards population health, and what has been termed ‘patient-centered care.’ You have to have a two-prong approach.”
There needs to be more research including longitudinal studies in vascular disease control in regions with higher disease burden, Dr. Dobbs said. “Practically, the findings support a need for more effective disease management and health/wellness programs in areas such as Eastern Kentucky and the Mississippi Valley.”
Dr. Howard said the use of technology could help address risk factors before a stroke, but could also be a vital tool for an individual at risk of having a second (or third) stroke.
For instance, she said, research has shown African-Americans develop hypertension earlier than whites. “Some of the data from REGARDS has shown that the same high level of blood pressure is doing more damage to African-Americans than it's doing to whites, and part of that is because they get it earlier so it has more time to do the damage — so early treatment and early diagnosis of risk factors and diet changes are especially important at a younger age.”
IMPROVING STROKE CARE IN EASTERN KENTUCKY
Michael Dobbs, MD, professor of neurology at the University of Kentucky and director of the Norton Healthcare/UK HealthCare Stroke Care Network in Lexington, has been training or working as a neurologist at the University of Kentucky since 1998 (apart from a few years spent serving in the Air Force).
Noting that eastern Kentucky was one of the regions with high cardiovascular mortality in the JAMA report, Dr. Dobbs told Neurology Today, “In my residency and as a junior attending taking care of stroke patients it became apparent to me that there simply weren't enough people and organizations working together in my region to prevent and treat cerebrovascular disease. We needed better coordination to manage stroke patients successfully, and more people working on the ground to manage and prevent risk factors such as hypertension and diabetes.”
So Dr. Dobbs and colleagues created a stroke care network in 2008 built on community outreach, prevention, standardization of stroke care, and quality improvement. “There are around 40 hospitals now in the network, with many in Eastern Kentucky participating. Millions of lives are within the umbrella of our affiliated hospitals. We are very proud of the work accomplished, which includes stroke education and one-to-one risk screening for more than 30,000 individuals.”
Creating sustainable and meaningful programs to address disease on a grass-roots level takes time, he acknowledged, but Dr. Dobbs remains optimistic. “There still aren't sufficient resources to manage vascular risk factors, with many primary care practices in Eastern Kentucky spread very thinly and with limited access. Today, in order to combat the physician shortage we face in Kentucky, the University of Kentucky is working to open three regional medical school campuses, one of which is planned for Eastern Kentucky.”
“It has made a difference,” he said.
EXPERTS: ON CARDIOVASCULAR MORTALITY BETWEEN 1980-2014