Prevention or Treatment: Why Is Heart Disease Mortality Dropping?

    • October 24, 2012

One of the greatest modern achievements in public health in the United States is the dramatic reduction in the number of lives lost to cardiovascular disease (CVD) over the past 40 years. Mortality rates have fallen 60 percent since the mid-1960s, but decades of research and analysis have failed to clarify exactly what was responsible for the decline.  “Is the answer risk factor control or the power of increasingly sophisticated medical interventions? There’s still no clear guidance for health policy-makers struggling to allocate scarce resources,” says David Jones, MD, PhD, a Robert Wood Johnson Foundation (RWJF) Investigator in Health Policy Research (2007).

Jones, a historian and professor of the culture of medicine at Harvard, and co-author Jeremy Greene, MD, PhD, an associate professor of the history of medicine at Johns Hopkins University School of Medicine, have conducted a historical analysis of the many factors considered in the debates over CVD prevention and the models employed by epidemiologists. Their assessment and commentary are explored in the article, “The Contributions of Prevention and Treatment to the Decline in Cardiovascular Mortality: Lessons From A Forty-Year Debate,” published in the October 2012 issue of Health Affairs.

More Work to Be Done

To understand the potential impact of determining the most effective method of reducing CVD mortality, it helps to know just how far some cardiovascular disease experts think we could still go in eradicating the disease. “There are cardiologists who believe that the natural rate of atherosclerotic [coronary artery] heart disease is zero percent. If this is true,” Jones says, “then how should we go about achieving that goal? Understanding the cause of the decline is also essential because the decline has begun to slow or reverse in certain populations. We are seeing upward trends in important CVD risk factors such as smoking and obesity in many places.”

For these reasons, Jones and Greene conclude that, “policy-makers must learn to open up the ‘black box’ of epidemiological models and of their own decision-making processes to produce the best evidence-informed policy.”  The problem is that following through on this straightforward advice is challenging in an environment where the limitations of the data and models used in cardiovascular epidemiology are not always clear to non-experts, including policy-makers.

Measuring the Impact of Prevention and Treatment

In the Health Affairs piece, Jones and Greene begin their discussion in the 1970s, when health officials first began reporting a CVD decline. They trace the research over the last four decades.  “I was first interested in the measurement of the impact of bypass surgery and angioplasty,” Jones says. “While doing that research, as part of my work as an Investigator in Health Policy Research, I discovered the larger decline debates.”

Focusing on key events such as the 1978 “Decline Conference,” held by the National Heart, Lung, and Blood Institute, the authors explore efforts to explain the successful battle against coronary artery disease. Clinicians and epidemiologists have debated the impact of many interventions, including the invention of specialized coronary care units, the use of beta-blockers and aggressive treatments for hypertension, the 1964 Surgeon General’s Report on Smoking and Health and the ensuing campaigns against smoking, and broader efforts to change diet and lifestyle.  In addition, to separate the possible interactions between these factors, researchers had to develop complex research models and simulations.

Despite many different methods used to assess the value of risk factor campaigns and medical advances, Jones and Greene report that “all forms of analysis have consistently shown the value of both risk factor control and medical intervention, crediting each about equally for the 60 percent decline in CVD mortality.”

Part of the problem, Jones notes, is that there are many powerful groups involved in CVD prevention and medicine who all see their form of intervention as the most effective. “If you are speaking to interventional cardiologists, they will say the key is angioplasty. If you are asking a surgeon, he will cite the value of bypass surgery.  Public health officials will most often cite advocacy, such as no-smoking programs.” 

“In addition, U.S. researchers tend to give slightly more credit to health care innovations, while the European researchers generally favor prevention,” Jones says. Some claims seem valid, he adds. As many researchers have noted, CVD decline correlates with the large reduction in smoking nationwide.  But other claims are problematic. 

“Surgeons have helped many patients, but they just don’t operate on the scale needed to have made a significant contribution to the decline,” Jones explains. “Complex epidemiological models are needed to gauge the impact of these interventions but these, in turn, rely on many assumptions that complicate their interpretation.”

Breaking Down Silos for a Solution

“For all our progress,” Jones continues, “CVD is still a leading cause of death in the United States.  If we could figure out the most effective use of resources, we could determine the best way to address the problem. Better communication between policy-makers and scientists is an important part of moving forward.  Policy-makers should work to understand the value and limitations of the various sophisticated models instead of taking the results for granted. They then need to integrate the models with the other factors that shape their decisions to produce the best evidence-based policy.”  Jones will offer a deeper exploration of these issues in his upcoming book, Broken Hearts: The Tangled History of Cardiac Care, to be published in January 2013.

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