Explaining the decrease in U.S. deaths from coronary disease, 1980-2000

TL;DR: Almost half the decline in U.S. deaths from coronary heart disease from 1980 through 2000 may be attributable to reductions in major risk factors and approximately half to evidence-based medical therapies.

Abstract: Following a peak in deaths from coronary heart disease (CHD) in about 1968, age-adjusted rates have declined by half. Two factors may have made critical contributions: a substantial decrease in prevalence of major cardiovascular risk factors such as smoking, high cholesterol, and high blood pressure; and major breakthroughs in evidence-based treatments including coronary bypass graft surgery, coronary angioplasty, thrombolytic therapy, and stents. The investigators used a validated statistical model, IMPACT, in an attempt to identify those factors chiefly responsible for the impressive decline in CHD mortality. Data were available for U.S. adults 25 to 84 years of age covering the years 1980-2000. Between 1980 and 2000, the age-adjusted death rate for CHD fell from 543 to 267 deaths per 100,000 population among men, and from 263 to 134 per 100,000 population among women. The result was 341,745 fewer CHD deaths in 2000. The U.S. IMPACT model explained approximately 90% of the decline in CHD deaths. • About 47% of the decline in deaths from CHD was ascribed to treatments, including secondary preventive therapy following acute myocardial infarction (AMI) or revascularization (11%), initial treatments for AMI or unstable angina (10%), treatments for heart failure (9%), revascularization for chronic angina (5%), and other treatments (12%). • Approximately 44% of the decline in CHD deaths was attributed to changes in risk factors, including reductions in total cholesterol of 0.34 mmol/L; systolic blood pressure of 5.1 mm Hg; the prevalence of smoking by 11.7%; and physical inactivity by 5%. These reductions were, however, partly offset by increases in body mass index and the prevalence of diabetes. These effects accounted, respectively, for increases of 8% and 10% in CHD mortality. The proportional contributions of specific treatments and risk factor changes to the overall reduction in deaths from CHD in the year 2000 were relatively consistent. The contribution of treatments for AMI remained consistently smaller than that of secondary prevention or treatments for heart failure, regardless of whether best, minimum, or maximum estimates were compared. These findings suggest the need for comprehensive strategies to treat and prevent CHD. Efforts will be needed to maximize the coverage of effective treatments and to actively promote population-based prevention through reducing risk factors.