The Contributions Of Prevention And Treatment To The Decline In Cardiovascular Mortality: Lessons From A Forty-Year Debate

Abstract

Mortality from coronary heart disease in the United States has fallen 60 percent from its peak in the mid-1960s. Cardiologists and epidemiologists have debated whether this decline reflects better control of risk factors, including lifestyle interventions to reduce smoking or intake of dietary fats, or the power of medical interventions, including defibrillators and therapeutics such as statins. Attempts to resolve this debate and guide health policy have generated sophisticated data sets and techniques for modeling cardiovascular mortality. Neither effort has provided specific guidance for health policy. Historical analysis of the debate over the causes of the decline, concomitant with development of cardiovascular modeling, offers valuable policy lessons about tensions among medical and public health strategies, the changing meanings of disease prevention, and the ability of evidence-based research and models to guide health policy. 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.

Decline in Cardiovascular Mortality

“…The importance of major risk factors in the prevention, pathogenesis, and clinical outcomes of CHD are well-establised; 46, 47 thus, it is not surprising that changes in risk factor levels are important contributors to the CHD mortality decline in the US 48, 49 However, the relative contribution of the role of primordial, primary, and secondary prevention in that decline has been very difficult to establish due to the lack of reliable data on time trends and incidence of cardiovascular events likely to be affected by those changes 50 and because they are likely to vary from country to country. 51, 52 Ideally, prevention studies need to account for the role and incidence of out-of-hospital sudden cardiac death (SCD) that is known to be the most common fatal cardiovascular event in most CHD patients.…”

Falling Coronary Heart Disease Rates

“…Others cited secondary prevention with associated acute and chronic medical care. Most agree that many factors played some role in the decline but dispute their relative contributions 5 . The relative contributions are more than an intellectual exercise as different prevention and treatment approaches have implications for resources and health policy.…”

“…Nonetheless, there have been numerous attempts to understand the magnitude, causes and relative impact of primary prevention, acute care and secondary prevention on CHD 5 . Cohort studies such as Framingham are used to describe the impact of risk factor change on outcomes 10 .…”

“…Cohort studies such as Framingham are used to describe the impact of risk factor change on outcomes 10 . Others have evaluated outcomes utilizing clinical trials or epidemiology data to estimate the magnitude of effect of various changes 5 . More complex models such as IMPACT utilize modeling techniques to include these many factors 11,12 .…”

Mild hypertension in people at low risk

“…5 6 The scale of the problem has resulted in large scale interventions 7 and national and international plans for action, such as the 2013 World Health Day. [5][6][7][8][9] Antihypertensive drugs have an important role in the treatment of malignant hypertension, secondary prevention of cardiovascular disease, and primary prevention for people at high risk: those with moderate to severe hypertension (≥160/100 mm Hg), diabetes, or chronic kidney disease. Debate continues, however, about the level at which treatment should begin and the appropriate targets for treatment (see supplementary box on bmj.com).…”